The synthetic substances were purified and characterized by using IR, MS, 1H-NMR and 13C-NMR spectrum and tested for antimicrobial and antifungal activity. Results: 16 derivatives on position 4 of 3-methyl-1 - (3-nitrophenyl) - 1H-pyrazol-5 (4H) - one were synthesized with the yield of ranging 40 - 80%.