Astrophysical parameters (MK class, colour excess, absolute magnitude, distance, effective temperature, mass and age) are derived from calibrations of the uvbybeta indices for the members of 253 double stars with O or B type primaries and faint secondaries. The photometric spectral classification is compared to the MK classes and the agreement is very good. The derived data together with spectroscopic and JHKL data indicate that these stars are likely to be members of physical systems. For 90% of the physical pairs the projected separations between the components is less than 25,000 AU. A majority of the physical secondaries are late type stars and 50% of them are contracting towards the zero-age main-sequence (ZAMS).