Born in Lisbon. In 1954 Siqueira shows for the first time at Portico Gallery and meets Almada Negreiros who invited him to work at his atelier. Fellowship to study in Paris, where he meets Christo who later paints his portrait. 1959 1st Gulbenkian Exhibition; represented Portugal at the I Paris Biennale, where he received a prize by the Association International des Critiques d’Art. Participated at the V São Paulo Biennale. Christo paints his portrait in Paris. 1962 Prize at the VI São Paulo Biennale. 1963 Prize Souza Cardoso, SNI, Lisbon. 1965 Participation at the VII São Paulo Biennale. 1966 Tokyo Biennale. 1966 Pierre Schlumberger acquires some of his works and invites him to visit USA . 1967 Solo exhibition at Catherine Viviano Gallery, New York. Collective at the Museum of Modern Art, New York, Abright Knox Museum, Buffalo; “First Kent Invitational” with Warhol, Lichtenstein, Raysse among others. 1968 Solo exhibitions at Catherine Viviano Gallery, New York and at the Bristol Museum, Rhode Island, USA. 1969 He has founded Judite Dacruz Gallery. 1969 till today, Siqueira has had several solo exhibitions and participated in several shows in Portugal and abroad. In 1998 inaugurated the subway station of Olivais, Lisbon decorated with tiles by the artist.