We investigate the doping of vanadyl–phthalocyanine by a fluorinated form of tetracyano-quinodimethane as an example of controlled doping of thin organic dye films by cosublimation of matrix and dopant. The electrical parameters of the films derived from conductivity and Seebeck measurements show that the results largelyfollow standard models used to describe the doping of crystalline semiconductors; e.g., a smooth shift of the Fermi level towards the valence states with increasing doping is observed. Other effects, like the superlinear increase of conductivity with the molar doping ratio, need the inclusion of additional effects like percolation. ©1998 American Institute of Physics.