The method of blazed holographic diffraction gratings fabricated by transformation of an original symmetric grating grooves into asymmetric ones using additional inclined irradiation by a monochromatic, or white light and repeated chemical etching have been developed. As photoresist material for gratings recording light-sensitive As2Se3 layers were used. Numerical modeling of the asymmetric groove formations was also carried out. The numerical results are in a good agreement with experimental groove profiles obtained by D3000 NanoScope. The asymmetry of produced gratings are clearly displayed in angular and spectral dependencies of the diffraction efficiency. The investigations shown that by changing the original grating formation parameters and the additional treatment conditions it is possible to produce blazed holographic gratings with designated groove form and blazed angle.