The energy required to form an electron‐hole pair in gallium phosphide has been measured using GaPp‐njunction diodes made from high‐purity‐level GaP materials. The values of &egr;GaPfor several GaP diodes for alpha particles ranged from 6.35 to 6.75 eV, with an average value of 6.54 ± 0.13 eV at 300°K. This value is smaller than that obtained by Goldstein and is very close to the value of 6.56 eV calculated from the experimental relationship &egr; = 2.596Eg+ 0.714(eV), which was derived previously from the experimental values of &egr; for Ge, Si, GaAs, and CdTe.