Аннотация:One of the important parameters for the interpretation of radio observations of WR stars is the temperature T of their envelopes. Correct radio measurement of T can be made only if the effective diameter of the star can be measured. The author analyzes the spectrophotometric variability of binary WR+OB stars. Two models of outer WR stellar envelopes are discussed: a high-temperature envelope and a low-temperature envelope with a hot core. The dependences of the width of spectral lines on ionization potential shows that in several cases, temperature is probably increasing toward the outer parts of envelopes.