The Global Ozone Monitoring Experiment (GOME) is a new, nadir-viewing instrument on the European Space Agency satellite ERS 2 which was launched in April 1995. With diode-array detector technology, spectra of the upwelling radiance are measured simultaneously at thousands of wavelengths in the UV, visible, and near-IR regions. Inversion of these measurements by appropriate algorithms allows the retrieval of the distribution of gaseous and particulate constituents, which modulate the radiance by absorption, emission, or scattering processes. Such a retrieval algorithm requires an accurate radiative transfer model to describe the propagation of light through the atmosphere. The model GOMETRAN has been specially designed to fulfill the needs of GOME, but it applies generally to other downward looking space instrumentation in the UV, visible, or near-IR. In this paper the model is described in the plane-parallel version, and the optimization of computational parameters and comparisons with other radiative transfer models is presented.¿ 1997 American Geophysical Union