While temperature control is usually employed in capillary electrophoresis (CE) to aid heat dissipation and provide acceptable precision, internal electrolyte temperatures are almost never measured. In principle, this limits the accuracy, repeatability, and method robustness. This work presents a fundamental study that combines the development of new equations characterizing temperature profiles in CE with a new method of temperature determination. New equations were derived from first principles relating the mean, axial, and inner wall electrolyte temperatures (TMean, TAxis, TWall). TMean was shown to occur at a distance 1/x3 times the internal radius of the capillary from the center of the capillary and to be a weighted average of 2/3TAxis and 1/3TWall. Conductance (G) and electroosmotic mobility (?-EOF) can be used to determine TMean and TWall, respectively. Extrapolation of curves of ?-EOF versus power per unit length (P/L) at different temperatures was used to calibrate the variation of ?-EOF with temperature (T), free from Joule heating effects. ?-EOF increased at 2.22 /A?C.