The temperature of a semiconductor wafer (160) is measured while undergoing processing in a plasma (168) environment. At least two pyrometers (162, 164) receive radiation from, respectively, the semiconductor wafer and the plasma in a plasma process chamber. The first pyrometer receives radiation from either the front or rear surface of the wafer, and the second pyrometer receives radiation from the plasma. Both pyrometers may be sensitive to the same radiation wavelength. A controller (170) receives signals from the first and second pyrometers and calculates a corrected wafer emission, which is employed in the Planck Equation to calculate the wafer temperature. Alternatively, both pyrometers are positioned beneath the wafer with the first pyrometer sensitive to a first wavelength where the wafer is substantially opaque to plasma radiation, and the second pyrometer is sensitive to a wavelength where the wafer is substantially transparent to plasma radiation.