The detonation velocity and performance were determined for four mixtures of triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane, TATP), ammonium nitrate (AN) and water (W) by cylinder expansion tests. The composition of these mixtures varied in the following ranges: 21-31% TATP, 37-54% AN and 19-32% W. The obtained results were compared with those of powdery 2,4,6-trinitrotoluene (TNT), AN-fuel oil explosive (ANFO) and emulsion explosive. It was found that the tested TATP/AN/W mixtures represent typical non-ideal explosives with relatively low critical diameter and with high sensitivity to initiation despite the high content of water due to the presence of the primary explosive (TATP). The detonation velocity is comparable to that of powdery TNT (at similar density). However, the acceleration ability is significantly lower than that of powdery TNT.