Reaction of 4-carboxy-3-cyano-pyrid-2-one la with SOC1 afforded the corresponding acid chloride 2. Treatment of 2 with different alcohols formed ester 3a,b. Condensation of 3a with hydrazine hydrate yielded the pyridazinone derivative 4. Reaction of N-acetyl pyridone lb with thiosemicarbazide and hydroxylamine hydrochloride gave thiosemicarbazone 5 and oxime 7 derivatives. Condensation of 4-carboxy-3-cyano-pyrid-2-thione 1c with ethyl chloroacetate and thiourea gave ester derivative 8 and pyrido [23-d] pyrimidine derivative 10. Quinazolone derivative 11 was prepared by reaction of Id with anthranilic acid. The reaction of 11 with several reagents was reported. The structure of the new compounds were established by analytical and spectroscopic measurements. Some new compounds showed interesting antimicrobial activities in vitro.