A procedure for the evaluation of the performance of a TG/MS system is proposed. This procedure includes tests for monitoring the mass-flow stability, the gas transfer delay, the evolved-gas condensation effect and the interferences of the coupling system on TGA and MSD specifications. The procedure was applied on an in-house constructed TG/MS system. The results of such evaluation procedure can be used for monitoring the performance of a specific TG/MS system and, thus, can be a basis for design improvements. in addition, they may be used for comparison of the results of different TG/MS systems, or for interlaboratory comparisons.