Spectral modelling and especially for massive stars is not a straightforward problem and over the past decades many advances have been made in this field. We now have sophisticated model atmosphere codes that allow to derive the stellar parameters. However, these codes are based on the assumption that the star is single and spherical which is no longer valid for the components of a binary system. On the other hand, observational studies indicate that binarity has an impact on the spectra. This is why we have developed a model called CoMBiSpeC (code of massive binary spectral computation) that specifically accounts for the impact of binarity on the spectra.