The diimide production kinetics for the reaction between hydrazine and hydrogen peroxide under alkali conditions were examined and the effects of Cu2+, boric acid and gelatin on the reaction kinetics were investigated. It has been found that cupric ion is a highly active catalyst for the reaction and both boric acid and gelatin enable the reaction to be controllable. While gelatin works as a stabilizer of cupric ions in the reaction system and reduces the catalytic activity of the cupric ions, boric acid functions as a promoter of the reaction. However, increasing the amount of gelatin or boric acid beyond a certain level does not lead to better control of the reaction. The activation energy of the reaction is 65.05 +/- 2.74 kJ/mol when catalyzed by the gelatin-cupric ion complex, and 35.86 +/- 0.75 kJ/mol when catalyzed by boric acid-promoted cupric ion system. The reaction was shown to be first order with respect to each of hydrazine and hydrogen peroxide. The viewpoint proposed in the literature that hydrazinium is involved in the rate-determining step of the redox reaction to produce diimide is not supported by the present study. (C) 2003 Elsevier B.V. All rights reserved.