Abstract The authors describe the photoelectric recording Raman spectrometer which they have built; it consists of the following parts: (a) a light source of the Toronto-type helical mercury arc furnished by ARL. (b) a monoohromator, which is the result of the transformation of a three-prism Huet spectrograph (9 A ̊ mm ), the scanning of the spectrum on a fixed exit slit, in front of the 1P21 photomultiplier tube is obtained by a plane mirror located between the camera lens and the focal plane. (c) a tuned amplifier giving the maximum positive reaction for the chopping frequency of light (about 31 cycles sec ) and a Brown recorder. The authors discuss the choice of optical and electronic parameters to obtain the following performances: 1. reproducibility of intensity measurements of about 2%. 2. a signal/noise ratio of about 500 : 1 is obtained for the 992-cm −1 Raman line, with a time constant of 4 seconds. 3. the resolution is excellent; the two lines 992 cm −1 of benzene and 1001 cm −1 of cyclo-hexane, are fairly well separated.