In this work, strip casting was introduced, and the necessity of heat treatment was explained from the viewpoint of DTA thermo-analysis. The results showed that: Five exothermic peaks appeared in the DTA curves of LPCNi3.55Co0.75Mn0.4Al0.3 alloy in which the intensity of the second and third peak decreased strikingly with the decrease of cooling rate. It was sensitive to the grain sizes. The intensity of the fourth and fifth peak showed less correlation with cooling rate, and they located in the range of theoretical recrystallization temperature. It was possibly introduced by recrystallization. In addition, segregation and internal stress also contributed to exothermic peaks. All heat variation had finished during the first temperature-rising period of DTA test, which implied that there was no irreversible phase transformation in the hydrogen storage alloys during the whole heated-cooled process. Four kinds of AB(5)-type hydrogen storage alloys in our work showed similar exothermic characteristics. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.