He drew his inspiration from the city and outlying areas of The Hague, where he lived his entire life apart from one brief interruption.
Louis was a member of the Hague Art Circle (‘Kunstkring’), an association of artists and art lovers founded in 1891. Here he held contacts with later renowned artists, such as; Jan Toorop (1858-1928), Ben Viegers (1886-1947) and Jan Knikker (1889-1957). In his work, Louis Soonius is strongly influenced by the impressionist painting style of The Hague School. Louis himself taught artist Arie Zwart (1903-1981) the technique of painting.
Louis Soonius painted with loose brush strokes his subjects on canvas or panel. He painted mostly outdoors. In the summer months, Louis painted, like his contender Isaac Israëls (1865-1934), the beach of Scheveningen. Around 1900 Scheveningen began to develop from a fishing village into a fashionable resort. From this time Louis began to paint sunny, colorful beach views with bathers and playing children. His beach views, where children ride on donkeys, are very popular. Sometimes these paintings gives also a view of the world famous Grand Hotel Kurhaus and Scheveningen Pier. Louis also regularly has painted in the nearby fishing village Katwijk and in the university city of Leiden.
Louis Soonius has painted many subjects, such as: port, sea and city views, winter landscapes, interiors, portraits and female nude. Louis’s artworks are exhibited in various Dutch and international museums.