YBa2Cu3O6+x was produced by self-propagating high-temperature synthesis (SHS) from copper, barium peroxide, and yttrium oxide. In contrast to previous studies, a stable reaction front coule be maintained even when using relatively large copper particles (smaller than 325 mesh). Large pellets (larger than 22 mm in diameter) were combusted at room temperature. Elevated ambient temperatures (400-500°C) were used to stabilize the combustion front movements in small pellets. A high-quality product may be obtained by a very short sintering at 950-970°C in an oxygen atmosphere following the SHS. The influence of copper-particle size, starting density and post-heat treatment were studied. An explanation of the influence of the copper particle size on the reaction stability is proposed.