The multiple chemical reaction paths taking place in the combustion wave of the ternary heterogeneous systems (Ti-N-2-O-2 and Nb-B-O-2), were experimentally studied. The Time-Resolved X-Ray Diffraction method was used for in-situ investigation of the mechanisms of phase formation during combustion in these systems. Ir was shown, that variation of the ignition temperature may lead to the significant changes of combustion temperature and velocity. It was experimentally confirmed that, this effect of nonuniqueness of the combustion parameters is a result of change in the chemical reaction path occurring in the combustion front. Analysis of the obtained data showed that this changing of reaction path may be a result of either thermodynamic or kinetic considerations depending on the investigated system.