The effects of additives Ti and LaCl3 on the hydrogen storage properties of NaAlH4 and LiAlH4 were investigated by the PCT (pressure-content-temperature) apparatus. NaAlH4 doped with LaCl3 and LiAlH4 doped with LaCl3 both show better capability of hydrogen release than the samples doped with Ti. The study on the first rehydrogenation cycle of NaAlH4 doped with 3 mol% LaCl3 finds that the dehydrogenation temperature has a marked decrease. In addition, the effect of LaCl3 content on hydrogen release of NaAlH4 is very obvious. The result indicates that the amount and rate of hydrogen release show the same change trends, increasing firstly and then decreasing with increasing of LaCl3 content. The sample doped with 3 mol% LaCl3 presents the best dehydrogenation properties in both the amount of hydrogen release and the desorption kinetics. The activation energy of the NaAlH4 sample doped with 3 mol% LaCl3 was measured to be 41.6 kJ/mol. This value is lower than that reported for the Ti-doped NaAlH4.