Positrons can be used to obtain unique information on solids. The life and annihilation of this anti-matter particle is extremely sensitive to the atomic and electronic environment. Studies of solid surfaces with monoenergetic positron beams have found increasingly interesting applications and many new techniques have been introduced with unique results. The more traditional techniques using polyenergetic positrons have been utilized in the study of internal surfaces closely related to catalysis. In this review different positron techniques are described and their applications in the field of surface science and catalysis are presented.