The authors verify that it is necessary to make a more accurate model of the processes occuring in the detonation wave, in particular, fragmentation of drops and mixing, the effect of the walls, change in the heat effect in the reaction zone owing to dissociaiton and recombination processes. The latter are studied in this work. Pseudoundercompressed detonation states in which the final state of the products in the stationary zone lying on the equilibrium Hugoniot adiabat lies below the tangent point are realizable in heterogeneous detonation in heptane-and hydrogen-oxygen mixtures. The necessary factor for the existence of such detonations is overenrichment of the starting medium with the condensed phase as compared with the mixture with the maximum heat effect (in the case of the heptane-oxygen mixture this condition is sufficient). The best possibilities for realizing such states appear if the pulsed action of the unevaporated condensed phase on the flow is small, which can be achieved by changing the diameter of the drops or using a mixture of fractions with markedly different drop sizes.