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The design and performance of a photon counting, two-channel spectroscopic system using the 6-W, 448-nm line of a cw argon ion laser is described. The two channels are formed by use of cylindrical optics and special slit mirrors set up following the exit slit of a conventional double spectrometer. The system is capable of dynamic, simultaneous measurements of either the concentrations of two gas species in cold flow or the temperature and concentration of a single gas species, such as N2, in a flame. Measurements are accomplished by recording the intensities of two spontaneous rotational Raman lines with spectral bandwidths between 0.04 and 0.08 nm. Up to 4096 samples (or reads from each of the two channels) can be recorded by a dedicated minicomputer at rates up to 10 kHz. Studies of a CH4 diffusion flame at sampling rates of 20 to 100 Hz and a room-temperature, axisymmetric C02 jet at rates up to 2.0 kHz were carried out. Analysis of the data from these studies include mean and rms profiles, probability density functions (pdf's), power spectral density functions, autocorrelation functions, cross correlation functions, and determinations of skewness and kurtosis in the pdf's and the C02 fluctuations.