  We present new calibrations of stellar parameters of O stars at solar
metallicity taking non-LTE, wind, and line-blanketing effects into account.
Gravities and absolute visual magnitudes are derived from results of recent
spectroscopic analyses. Two types of effective temperature scales are derived:
one from a compilation based on recent spectroscopic studies of a sample of
massive stars - the ``observational scale'' - and the other from direct
interpolations on a grid of non-LTE spherically extended line-blanketed models
computed with the code CMFGEN (Hillier & Miller 1998) - the ``theoretical
scale''. These Teff scales are then further used together with the grid of
models to calibrate other parameters (bolometric correction, luminosity,
radius, spectroscopic mass and ionising fluxes) as a function of spectral type
and luminosity class. Compared to the earlier calibrations of Vacca et al.
(1996) the main results are: 1) the effective temperature scales are cooler by
2000 to 8000 K, the reduction being the largest for early supergiants; 2)
bolometric corrections are lower by 0.1 mag for a given temperature, and are
lower by 0.3 - 0.6 mag for a given spectral type; 3) luminosities are reduced
by 0.20 to 0.35 dex; 4) Lyman ionising fluxes are lower by 0.20 to 0.80 dex. We
provide calibration tables for each luminosity class and for both types of Teff
scales.
