Hazards caused by detonation of hydrocarbon-air mixtures have been a matter of concern for a long tome. In this paper, critical initiation energy of detonation of some hydrocarbon-air mixtures have been measured in confined (rectangle shock tests) and unconfined (plastic bag tests) condition. Based on the concept initiation energy on detonation under unconfined condition is presented. Detonation safety analysis of the studied hydrocarbons is carried out using the experimental results.