Acoustic emission (AE) signals, obtained during the isothermal oxidation of 2.25Cr-1Mo steel at 773 K, 873 K, 973 K and 1073 K, have been analyzed. The results indicated that the rate of occurrence of AE events and consequently the total number of AE events generated during isothermal oxidation at these temperatures increased with an increase in the oxidation rate. Variation in the temperature of oxidation did not show any variation in the root mean square (RMS) level of the AE signals. The b-parameters obtained from a logarithmic cumulative amplitude distribution plot indicated that the strength of the AE signals did not change during isothermal oxidation carried out at these temperatures. Different event rates, and consequently the difference in the total number of AE events generated during isothermal oxidation at these temperatures, are indicative of the increased rate of energy release associated with the growth of oxide layers formed at higher temperatures. The rate of energy release has been found to be higher for higher temperatures of oxidation.