The equilibrium constant for the formation of diethanolamine carbamate was determined experimentally at (303, 313, 323, and 331) K for ionic strengths up to 1.8 mol dm(-3), the inert electrolyte being NaClO4. A linear relationship was found to hold between log K and I-0.5. The thermodynamical constant has been determined and expressed by the equation log K-1 = -5.12 +/- 1.781 x 10(3) K/T.