Hydrogen-induced phase decomposition of pseudobinary intermetallic compounds Tb1-xDyxFe2 (where 0 less than or equal to x less than or equal to 1) is investigated at temperature 600degreesC and hydrogen pressure 16.2 kPa. It is shown that by increasing the Dy content in an alloy the rate of decomposition markedly decreases. On the basis of data obtained due to the analysis in the context of Avrami's theory, a conclusion has been made that the phase decomposition of intermetallic compounds Tb1-xDyxFe2 occurs with the decreasing rate of ferromagnetic alpha-Fe phase nucleation, (C) 2002 Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.