The kinetics of the reduction of sodium sulfate mixed with sodium titanate by both CO and H$ sb2$ are studied in a thermogravimetric system. The H$ sb2$ reduction kinetics are described by the nucleation and growth model up to 60% conversion and by the shrinking core model for higher conversions. The CO reduction kinetics are described by nucleation and growth model up to 95%. Both the H$ sb2$ and CO reduction are accelerated by the initial presence of Na$ sb2$S and are catalyzed by iron oxide. The influence of H$ sb2$ and CO concentrations, H$ sb2$O and CO$ sb2$ concentrations and mass fraction of sodium titanate is also investigated. The combustion product of a mixture of kraft black liquor and TiO$ sb2$ is even faster reduced by H$ sb2$ and CO than the model mixtures.