A presentation of the values for the Pu²³⁹ fission cross section f factor extended into a higher energy range than previously reported in BNL-250. The values were obtained by integrating the standard expression defining the f factor on the Hanford IBM-CPC equipment. The un-fit experimental data of Leonard, as corrected for resolution and doppler effect, was used above 0.03 ev being attached to an analytic fit applicable below this point. Results are shown on the accompanying graph.