Hazards caused by leakage of hydrocarbons have long been a problem. In this paper, the critical initiation energy and explosion limits of some hydrocarbon-air mixtures have been measured in confined (rectangle shock tube) and unconfined (plastic bag) condition tests. Two dimensionless parameters are suggested to compare the fire and explosion hazards of different hydrocarbons. Additionally, a series of experiments was performed to determine the influence of chemical additives on the fire and explosion hazards of some hydrocarbon-air mixtures in confined (rectangle shock tube) tests. These results relate directly to flammability and reactivity of hydrocarbon air mixtures. Such measurements are very important for hydrocarbon safety.