This thesis deals with the critical theory of contemporary artistic production using examples of artworks with ephemeral and transitory urban characters. The widespread definition of ephemeral is usually used to describe a work of art that cannot be preserved in its original form and cannot permanently embody itself in any permanent object. Such (ephemeral) works manifest in the form of records; artistic documentation (photo, draft, sketch, text, video), which conveys information about an absent work of art, whereby the process of passing gives the artwork a special status. Although the artworks of ephemeral character and the idea of ephemerality exist throughout the history of art, the concept of ephemeral art started to appeare in the 1960s as a response and a critique of the Western artists and art critics to the established art and the tendency to the commodification of art. In this thesis, ephemeral art is correlated with the appearance of the dematerialization of art and the arrival of post-minimal and preformance art practices. The examples of ephemeral art in this thesis are the ones from the public space, especially the ones that engage in dialogue with reality, context, and the audience. Emphasis is placed on the examples of ephemeral art that denote different variants of relational practices in the public sphere, which point to the ambiguity of the relationship between the artistic product, the artist, and the audience. In conclusion, a critical presentation of an artwork by the artist Ivan Kožarić “Haystack” attempts to unify the main determinants of ephemeral art and relational aesthetics in urban space.