Integral diffusion coefficients were measured for potassium hydroxide over a concentration range of 0.1 M to 11 M at 1, 10, and 25 degrees C using the simplified diaphragm cell procedure of Mills, Woolf, and Watts. Differential diffusion coefficients were calculated using the iterative regression method of Stokes over the same concentration and temperature range. An empirical correlation relating the differential diffusion coefficients as a function of temperature and concentration was made with a standard error of 8 x 10(-7) cm(2).s(-1) and an average deviation of 5 x 10(-7) cm(2).s(-1).