We have observed 10 luminous blue stars in M 33 at intermediate dispersion and have determined spectral types and luminosity classes from the blue and red spectrograms by comparing with galactic and SMC stars. Halpha_ profiles have proved to be very useful in disentangling luminosity and metallicity effects, and constitute a valuable diagnostic when comparing spectral classifications in galaxies with different metallicities. We derive qualitative estimates of the stellar metallicities which range from solar to SMC-like and are broadly consistent with abundance gradient results obtained for M 33 from Hii region studies. Comparison of the new data for B 324 with previous work shows that there is evidence for significant spectral variability strongly suggesting an LBV nature for this star.