A presentation of an approximate analytic model of ozone photochemistry, including reactions with hydrogen compounds, for the atmospheric region between 15 and 60 km. The model is used to study time-dependent processes, sensitivity of the equilibrium-concentration values to uncertainties in reaction rates, and variations in the equilibrium ozone concentration with latitude and season. The reaction scheme used is a simplified version of one used previously by B. G. Hunt. Approximate equilibrium relations are derived and are then used to obtain simplified equations to describe the behavior of a complete system. Intended to clarify the roles of various possible reaction schemes for ozone, the study should be of interest to those concerned with meteorological problems in this portion of the atmosphere and to those concerned with laboratory investigation of the chemistry of oxygen/hydrogen systems. 35 pp. Ref.