[en] Fission-product decay energy-release rates were measured for thermal-neutron fission of ²⁴¹Pu using samples of 1 and 5 μg. The resulting beta- and gamma-ray emission spectra were recorded for times-after-fission between 2 and 14,000 s. The data were obtained for beta and gamma rays separately as spectral distributions, N(E/sub γ/) vs E/sub γ/ and N(E/sub β/) vs E/sub β/. For the gamma-ray data the spectra were obtained with a NaI detector, while for the beta-ray data the spectra were obtained by use of an NE110 detector with an anticoincidence mantle. The raw data were unfolded to provide spectral distributions of modest resolution. Total yield and energy integrals as a function of time after fission were obtained from integration over E/sub γ/ and E/sub β/. The final differential spectral and integral data are given in tabular and graphical form. The total integral energy-release data are compared with similar data previously obtained for ²³⁵U and ²³⁹Pu. Following a pulse of fissions the total decay-heat power for ²⁴¹Pu fission is greater by approximately 5 percent than that for ²³⁵U for times after a fission pulse less than 2500 s, and greater by up to 40 percent than that for ²³⁹Pu. For times after a fission pulse greater than 5000 s the decay-heat power for ²⁴¹Pu asymptotically approaches that for ²³⁹Pu, and is less than that for ²³⁵U by approximately 25 percent at 14000 s. On an infinite irradiation basis, the decay-heat power for ²⁴¹Pu is equal to that for ²³⁵U for times after shutdown less than 100 s, less than that for ²³⁵U for times after shutdown greater than 300 s. The decay-heat power for ²⁴¹Pu is greater than that for ²³⁹Pu for times after shutdown less than 50 s, asymptotically approaching and becoming equal to the ²³⁹Pu decay-heat power for longer times after fission. 97 figures, 99 tables