Plasma heating and current drive in tokamaks by means of high power electron cyclotron waves result in generating non-Maxwellian electron distribution functions. The properties of the radiation emitted at the electron gyro frequency and its harmonics by such non-thermal distributions are investigated. The electron distribution function is evaluated by means of a 3-D bounce averaged Fokker-Planck code for some typical heating scenarios, and the related emission spectra are computed. It is shown that the peculiar features of the spectra are sensitively related to subtle kinetic processes such as quasi-linear flattening of the electron distribution or formation of perpendicular tails and toroidal effects on the electron orbits, which are known to play an important role in electron cyclotron heating and current drive.