A model of mass transfer during gas absorption in gas-liquid plug flow accompanied by irreversible chemical reaction of the first order and zero order is suggested. The expressions for coefficients of mass transfer during chemical absorption from a single Taylor bubble are derived in the approximation of the thin concentration boundary layer in a liquid phase. Under the assumptions of a perfect liquid mixing in liquid plugs recurrent relations for the dissolved gas concentrations in the n-th liquid plug and mass fluxes from the n-th Taylor bubble are derived. The total mass fluxes in gas-liquid plug flow during chemical absorption are determined. In the limiting case of absorption without chemical reaction the derived formulas recover the expressions for mass transfer during physical absorption in gas-liquid plug flow. Theoretical results are compared with available experimental data.