Palmitic acid was extracted from Over used oil according to the method described by Hanaa Soliman etal1. Where the over used cooking oil was filtered off, then it was hydrolyzed with distilled water in high pressure reactor at 250˚C and 2 MPa as described by Sonntag etal2 to produce glycerol and mixture of fatty acids. Fatty acids mixture was cooled at 7˚C in order to precipitate all saturated fatty acids, which were then filtered off, Palmitic acid was extracted from this mixture by means of supercritical CO2 extractor at pressure of 35.0 MPa and temperature of 328˚K according to Maheshwari etal3, followed by its methylation and confirmation by GC mass. Then it was used as precursor for production of a different heterocyclic compounds, which were then tested for their antimicrobial activities. Thus the long-chain methyl palmitate was interacted with hydrazine hydrate4 to produce the corresponding acid hydrazide (2), that was then treated with phenyl isothiocyanate, furnished the corresponding thiosemicarbazide 4. The later was reacted with ethyl chloro(arylhydrazono) acetate 5a-b in dimethylformamide, in the presence of triethylamine, afforded thiadiazole derivatives 7a-b . A solution of thiosemicarbazide 4 in ethanol was interacted with the α-haloketones 9 in the presence of triethylamine, produced the parallel thiadiazine 12. The structure elucidation of all synthesized compounds is based on the elemental analysis and spectral data (IR, 1H NMR, 13C NMR and MS).