Abstract: A new series of 2-(ortho & para substituted phenoxy)-1-(3-(3-chloro-4-methoxyphenyl)-5-(substituted phenyl)-4,5-dihydropyrazol-1-yl)ethanone were synthesized. Ortho and para substituted phenol was refluxed with ethylchloroacetate in dry acetone in presence of anhydrous potassium carbonate to yield ethyl (ortho & para substituted phenoxy) acetate (1). The substituted ester on reaction with hydrazine hydrate yields 2-( ortho & para -substituted phenoxy) acetohydrazide (2). Chalcones (3a-3j) were prepared from the reaction between substituted aromatic aldehydes and 3-chloro-4-methoxy acetophenone in presence of a strong base. (2) On reaction with chalcones afforded the pyrazoline derivatives. The chemical structures of these compounds were confirmed by means of IR, 1H NMR, mass spectral data and elemental analysis. Newly synthesized compounds were screened in vitro for their antimicrobial activity against varieties of gram positive and gram negative bacterial strains and fungi strains Candida albicans & Aspergillus nigar at 100 μg/mL.