The effects of sodicity, osmotic water potential {Ψ_s}, temperature and their interaction on the seed germination processes of the medicinal tree Cassia fistula was carried out. The present data indicated that, the radicle emergence was greatly affected by the interaction between incubated temperature and sodicity {T × SAR}, but Ψ_s had a non-significant effect. Regardless of sodicity, the optimal temperature produced a maximum value on the germination rate index under relatively high Ψ_s. Conspicuously, the Ψ_s had a predominant role in the elongation of both radicle and hypocotyl. The same effect of Ψ_s on the fresh biomass of embryonic axis organs and storage tissue of seedlings was true, whereas, the temperature effect had a sub- dominant role. The moderate Ψ_s and sodicity levels exerted high biomass accumulation efficiency under the optimal temperature. At the same temperature, the seedling vigor index was reached to the highest value at sodicity level {20%} and moderate Ψ_s. The correlation between the seedling water content and germination characteristics were discussed.