In order to test massive star evolution above 25 M⊙, we perform spectral analysis on a sample of massive stars in the Small Magellanic Cloud that includes both O stars as well as more evolved Wolf-Rayet stars. We present a grid of non-LTE stellar atmospheres that has been calculated using the cmfgen code, in order to have a systematic and homogeneous approach. We obtain stellar and wind parameters for O stars, spectral types ranging from O2 to O6, and the complete sample of known Wolf-Rayet stars. We discuss the evolutionary status of both the O and WR stars and the links between them, as well as the most likely evolutionary path towards black hole formation in a low metallicity environment, including testing theoretical predictions for mass-loss rates at low metallicities.
