Abstract: The paper reports specially designed experimental methods for calibratingphotomultiplier tubes used in the multichannel fast-pulse-detection systein ofThomson scattering measurements for nuclear fusion devices. The most importantparameters of the photomultiplier tubes to be calibrated include: linearity ofoutput electric signals to input light signals response time of pulsed light, spectralresponse, absolute responsibility, and sensitivity as a function of the chain voltage.The calibrations of all these parameters are carried out by using EMI 9558 Band RCA 7265 photomultiplier tubes respectively. The experimental methodspresented in the paper are common to those quantitative measurements thatrequire photomultiplier tubes as detectors.