The procedure of deriving flame temperature and major species concentrations by fitting measured Raman spectra in hydrocarbon flames is described. The approach simplifies the calibration procedure to determine temperature and major species concentrations from the measured Raman spectra. The calculations of the Raman spectra are performed using data online positions and cross sections from the current literature. Utilizing all spectral information for deriving temperature and major species concentrations substantially increases accuracy, while interferences can easily be detected and filtered out of the measured spectrum. Temperatures from the separate Raman spectra of N-2, H2O, O-2, CO2 and CO are systematically compared with each other over the span of more than 1,700 K. The agreement between them is generally better than 100 K. The developed procedure also allows us to determine the mole fractions of the major species with absolute accuracy of +/- 10 %.