In this study, a series of 4-(4-methyl-phenyl)-substituted phthalazin-1-one derivatives have been synthesized with the combination of rapid microwave synthesis and phase-transfer catalyst methodology, which is characterized by very short reaction times and easy workup procedures and which can be exploited to generate some novel phthalazinone heterocycles. Substituted phthalazin-1-one derivatives have been synthesized from phthalyl derivatives as starting material. The structures of these compounds were confirmed by NMR and mass spectral studies.