His earliest works were related to land art (1967-1969) and later works to performance, body-art and video. Oppenheim surpassed these styles in the early 1980s with the creation of what he calls machine pieces, which are complex randomly functioning constructions. In the mid-1980s, his sculptures were based on the transformation of everyday objects, which acquired large-scale dimensions and blended sculpture and architecture. He has exhibited at the Institute for Contemporary Art, PS1, New York (1991), the Palau de la Virreina in Barcelona (1994), Fundação Serralves in Oporto (1996), the Helsinki City Art Museum (1997), the Círculo de Bellas Artes in Madrid (2004) and the Museum of Contemporary Art of San Diego, California (2009). His work is present in the collections of the Tate Gallery of London, the Stedelijk Museum of Amsterdam, the Museum of Modern Art in New York, the Musée d’Art Moderne de la Ville de Paris, the Musée National d’Art Moderne in Paris, the Museo Nacional Centro de Arte Reina Sofía in Madrid and there are outdoor sculptures in cities such as Copenhagen, Victoria (Australia), Berlin and Palma, among others.