Irradiation-induced embrittlement of a 2.25CrlMo is investigated by means of small punch testing and scanning electron microscopy (SEM). The ductile-brittle transition temperature (DBTT) determined by the small punch test is much lower than that determined by the standard Charpy test. There are some irradiation-induced embrittlement effects after the steel is irradiated at about 270 degrees C for 46 days with a neutron dose rate of 1.05 x 10(-8) dpa s(-1) and at about 400 degrees C for 86 days with a neutron dose rate of 1.75 x 10(-8) dpa s(-1). In addition, there is some temper embrittlement after the steel is aged at about 400 degrees C for 86 days. (C) 2000 Elsevier Science B.V. All rights reserved.