The shock initiation of detonation in nitromethane, liquid TNT, and single‐crystal PETN has been studied using a numerical method for solving the reactive fluid‐dynamic equations. Agreement was obtained with previously reported experimental results.Studies were made which explain in detail the mechanism of initiation of detonation at hot spots created by the interaction of a shock with an inhomogeneity. Energy transfer is accomplished by shocks and rarefactions. It is shown how experimentally observed criticality in bubble size can be related to the divergence rate of the shock, and to other features of the fluid flow. The relation of these results to initiation of detonation in inhomogeneous explosives is discussed.