The data given recently by Shpirt (Water Res.15, 739–743, 1981) on the stripping of ammonia from aqueous solutions is examined; it is shown by means of a material balance that the gas leaving the liquid column must be very nearly saturated by ammonia, contrary to Shpirt's claims.A simple theory for batch absorption and stripping is developed in an Appendix that accounts for the increased depletion or saturation of the solute in the bubbles as they rise through the liquid.