The number of paints of contact between particles of fuel and particles of oxidant in various pyrotechnic mixtures have been calculated on the assumption that the fuel and oxidant powders consist of uniform spherical particles of different sizes. The calculated numbers of contact points are compared with the experimental burning rates of these mixtures. In spite of the severe approximations made, there is a qualitative connection between the calculated numbers of contact points, N-R, and the measured burning rates, nu, of those pyrotechnic compositions which are presumed to burn mainly via solid-solid reactions.