Josep Maria Mestres Quadreny (born 4 March 1929 in Manresa) is a Spanish composer.
He studied sciences at the University of Barcelona, taking lessons in composition from Cristòfor Taltabull. In 1968 he started the Catalan Group of Contemporary Music (Conjunt Català de Música Contemporània), and in 1976 the Catalan Instrumental Group (Grup Instrumental Català) with Carles Santos. He also founded the Phonos Laboratory of Electroacoustic Music in 1973.
His output includes incidental music for theatre and cinema, musicals, ballet, opera and instrumental music. He has also collaborated with visual artists, including Joan Miró, Antoni Tàpies and Joan Brossa.
In addition to his compositional activities, he has taught at the Darmstadt New Music Courses and the Latin American Course of Contemporary Music in Brazil.
He is charmain of Joan Brossa Foundation and emeritous member of board of trustees of Joan Miró Foundation.