AbstractWe investigated the reactions in composite thermite layers consisting of Al, CuO, and Cu2O nanoparticles formed by electrophoretic deposition on a titanium substrate. The composition determined the reaction propagation rates and heat effects in oxygen and oxygen‐free atmospheres. It was found that a stable self‐propagating exothermic reaction in the aluminum‐copper oxide layer takes place in the range of 50–80 wt.% of Al. The maximum values of the measured heat effects also fell in this range. At the same time, the calculation following the stoichiometry of the reaction shows the optimal range of the Al amount is 10–20 wt.%. To explain this fact, we proposed a model based on calculating the probability of contact between Al and CuO particles depending on the average particle size and their concentration. The model is based on the calculation of solid angles, which means that the exact value of the contact area does not play a decisive role in this case.