This work investigated the effects of annealing and testing temperature on the pseudoelastic stress hysteresis of a Ti-50.2at%Ni alloy. It was found that the stress hysteresis of pseudoelasticity and the strain span of the stress plateau increased with increasing annealing temperature. For specimens annealed at the same temperature, the stress hysteresis of pseudoelasticity was found to decrease with increasing testing temperature. The effects of testing temperature on pseudoelastic behaviour are attributed to the influences of the R-phase transition during the deformation whereas the effects of annealing are interpreted in terms of the modification to metallurgical conditions of the matrix.