Theo (Theophile) van Rysselberghe (23 November 1862, - 14 December 1926), was a Belgian neo-impressionist painter, who played a pivotal role in the European art scene at the turn of the century.

Born in Ghent to a French-speaking bourgeois family, he studied first at the Academy of Ghent under Theo Canneel and from 1879 at the Academie Royale des Beaux-Arts in Brussels under the directorship of Jean-Francois Portaels. The North African paintings of Portaels had started an orientalist fashion in Belgium. Their impact would strongly influence the young Theo van Rysselberghe. Between 1882 and 1888 he made three trips to Morocco, staying there a total of one year and half.

Barely 18 years old, he already participated at the Salon of Ghent, showing two portraits. Soon afterwards followed his Self-portrait with pipe (1880), painted in somber colours in the Belgian realistic tradition of that time. His Child in an open spot of the forest (1880) already departs from this style and he sets his first steps towards impressionism. Yet soon he would develop his own realistic style, close to impressionism. In 1881 he exhibited for the first time at the Salon in Brussels.

The next year he travelled (following in the footsteps of Jean-Francois Portaels) extensively in Spain and Morocco, together with his friend Frantz Charlet and the Asturian painter Dario de Regoyos. He especially admired the 'old masters' in the Museo del Prado. In Seville they met Constantin Meunier, who was copying Pedro Campana's Descent from the Cross. From this Spanish trip stem the following portraits : Spanish woman (1881) and Sevillan woman (1882), already completely different in style. When he set foot in Tanger at the end of October 1882, a whole new world opened up for him: so close to Europe and yet completely different. He would stay there for four months, drawing and painting the picturesque scenes on the street, the kasbah and in the souk: Arabian street cobbler (1882), Arabian boy (1882), Resting guard (1883).

Back in Belgium, he showed about 30 works of his trip at the "Cercle Artistique et Litteraire" in Ghent. It was an instant success, especially The kef smokers, The orange seller and a seascape The strait (setting sun), Tanger (1882).

Theo Van Rysselberghe was one of the prominent co-founders of the Belgian artistic circle Les XX on 28 October 1883. This was a circle of young radical artists, under the patronage, as secretary, of the Brussels jurist and art lover portrait of Octave Maus (1856-1919). They rebelled against the outmoded academism of that time and the prevailing artistic standards. Among the most notable members were James Ensor, Willy Finch, Fernand Khnopff, Felicien Rops, and later Auguste Rodin and Paul Signac. This membership brought van Rysselberghe in contact with other radical artists, such as James Abbott McNeill Whistler, who had exhibited in Les XX in 1884. His influence as a portrait painter can be seen in van Rysselberghe's portrait of Octave Maus as a dandy (1885). Van Rysselberghe would paint several portraits of Octave Maus and his wife between 1883 and 1890.

In November 1883 he left again, together with Frantz Charlet, for Tanger. During his stay of one year, he was in constant correspondence with portrait of Octave Maus, urging him to accept several new names for the first exhibition of "Les XX": Constantin Meunier, Alfred Verwee, William Merritt Chase. (He had met him in 1883 in Haarlem.) In April 1884 he visited Andalucia in the company of the American painter John Singer Sargent and the gentleman-painter Ralph Curtis. He also invited them to the exhibition in Brussels. This time, van Rysselberghe tried to surpass himself. His large, exotic painting Arabian phantasia, a theme introduced by Eugene Delacroix, is his best known work from this period. It is bathed in the harsh light of the hot Moroccan sun. From now on van Rysselberghe would be obsessed by light. But lack of funds forced him to return to Belgium at the end of October 1884.

At the second show of Les XX in 1885 Theo van Rysselberghe showed his Arabian phantasia and other images and paintings from his second Moroccan trip, such as Abraham Sicsu (interpreter in Tanger) (1884).

Yet his next portraits are in rather subdued colours, using different black or purple gradations contrasting with light colours: Jeanne and Marguerite Schlobach (1884), portrait of Octave Maus (1885), Camille Van Mons (1886), Marguerite Van Mons (1886) (to be compared with Portrait of Gabrielle Braun (1886) by Fernand Khnopff). He saw the works of the impressionists Monet and Auguste Renoir at the show of Les XX in 1886. He was deeply impressed. He experimented with this technique, as can be seen in Woman with Japanese album (1886). This impressionist influence became prominent in his paintings Madame Picard in her Loge (1886) and Madame Oscar Ghysbrecht (1886) (painted in a palette of bright colours). In 1887 he painted some impressionist seascapes at the Belgian coast : Het Zwin at high tide (1887). Because of his growing ties with the Parisian art scene, Octave Maus sent him as a talent scout to Paris to look out for new talent for the next exhibitions of Les XX.

His famous portrait of Alice Sethe (1888) in blue and gold would become a turning point in his life. This time he used merely points in the portrait. She would later marry the sculptor Paul Dubois. Her sister, Maria Sethe, also a model of van Rysselberghe, would marry the renowned Art Nouveau architect Henry Van de Velde. In that period he made many Neo-impressionistic portraits, such as the portrait of his wife Maria and their daughter Elisabeth. He had married Marie Monnom in 1889. They went on their honeymoon to the south of England and then to Brittany. This would also result in a number of Neo-impressionistic paintings. In Paris he had a meeting with Theo Van Gogh and managed thus to invite Vincent Van Gogh to the next exhibition in Brussels. That is where Van Gogh sold Vigne Rouge in Montmajour to Anna Boch, the only painting he ever sold.

After 1903, his pointillist technique, which he had used for so many years, became more relaxed and after 1910 he abandoned it completely. His strokes had become longer and he used more often vivid colours and more intense contrasts, or softened hues. He had become a master in applying light and heat in his paintings. His Olive trees near Nice (1905) remind us of the technique used by Vincent Van Gogh. These longer strokes in red and mauve become prominent in his Bathing ladies under the pine trees at Cavaliere (1905). After some prospecting, touring on his bike, together with his friend Henri-Edmond Cross, of the Mediterranean coast between Hyeres and Monaco, he found an interesting spot in Saint-Clair (where Cross already resided). His brother (and neighbour), the architect Octave van Rysselberghe, built him there a residence in 1911. He retired now to the Cote d'Azur and became more and more detached from the Brussels art scene.

Here he continued painting, mostly landscapes of the Mediterranean coast, portraits (of his wife and daughter, and of his brother Octave) and decorative murals. From 1905 on, the female nude becomes prominent in his monumental paintings : "After the bath" (1910). His painting The vines in October (1912) is painted in lively colours of red, green and blue. One of his last works was Girl in a bath tub (1925).

At the end of his life, he also turned to portrait sculpture, such as the Head of Andre Gide.

He died in Saint-Clair on 14 December 1926 and was buried in the cemetery of Lavandou, next to his friend and painter Henri-Edmond Cross. Much of the works of one of the greatest neo-impressionist painters still remain in private collections. They can only rarely be seen. One recent occasion was the retrospective Theo van Rysselberghe in Brussels and later in The Hague between February and September 2006. In November 2005, his work Port Cette (1892) fetched a record 2.6m Euro at an auction in New York.

His brother Octave van Rysselberghe (1855-1929) was a famous Belgian architect, who collaborated with Joseph Poelaert and Henry Van de Velde.