The objective of the work presented here is to theoretically investigate the absorption of a gas into a liquid flowing in laminar flow over a sphere with a second-order irreversible chemical reaction occurring between the absorbed gas and a nonvolatile solute present in the liquid. Commonly used simplifications in the diffusion-reaction equations and for the liquid velocity profile and the liquid film thickness on the sphere are investigated, and it is found that, under the experimental conditions usually encountered, these simplifications are justified. Numerical results for the absorption rate are presented graphically in two figures which may be used to estimate the second-order kinetic rate coefficient for the reaction between the absorbed gas and the nonvolatile liquid-phase solute. A criteria is developed for the conditions under which a second-order reaction may be considered to be pseudo-first-order.