We report second harmonic generation in the ZnS-based materials. Self-activated ZnS, ZnS:Cu,Br and ZnS:Cu,Al were studied. Phosphor powders were subjected to the 30mJ pulses of YAG infrared laser. Wavelength of the generated green emission was 532 nm, exactly one half of that of incident laser light (1064 nm). It is shown that high copper content in the phosphor is crucial for the non-linear properties.