[en] A Monte Carlo Code, PHOEL, is described for generating the initial energies of Compton and photoelectrons in water irradiated by photons with an arbitrary energy spectrum. An infinite, homogeneous water phantom is assumed in which the photon spectrum is uniform throughout. The neglect of pair production does not represent a significant omission for photons with energies below about 10,000 keV. The code PHOEL was written specifically to provide a source term for a Monte Carlo electron energy degradation and transport code for liquid water being used to study the relative biological effectiveness (RBE) of low-LET radiations at low doses. The basic numerical data used in PHOEL and their mathematical treatment are described as well as the operation of the code. Copies of the program are available from the Radiation Shielding Information Center at Oak Ridge National Laboratory. Some numerical computations which have been made for verification of the code are briefly described. The code processes 1000 photons at 200 keV in less than 2 s on the IBM 360/91. Because of multiple Compton scattering, the processing of higher-energy photons takes somewhat longer. The code has options for printing the electron energies and/or writing them on tape or disc. 1 figure, 2 tables