The exothermic chemical conversion of energetic composites based on porous silicon, prepared by electrochemical etching of a single-crystal n-type silicon wafer, and barium perchlorate was studied using high-speed video filming. It is found that the mixtures under study can show either local chemical conversion, which occurs in and around the initiation spot, and the self-sustained propagation of the exothermic reaction over the material volume. After subjection of the energetic composites to compression in a closed container, it became possible to determine the upper estimate of the chemical reaction front propagation speed, equal to 89 m/s, and classify the process as burning. Keywords: porous silicon, energetic composite, barium perchlorate, exothermic reaction, self-sustained burning, burning rate.