The present book comprises three chapters:Chapter I. Introduction: A full literature survey around the subject of study.Chapter II. Experimental: This chapter Involves materials, procedure, equipment and characterization of the synthesized compounds.Chapter III. Results and discussion: This chapter describes a facile and efficient synthesis of triazolo[3,4-b]thiadiazines, triazolo[4,3-b]tetrazines and triazolyl-N-N`-triazoles from reaction of 1,2,4-triazole derivative or its Schiff's base with different hydrazonoyl chlorides. This chapter also describes a facile and efficient MCR for synthesis of 2-thiazolyl pyridines from reaction of 2-bromoacetyl pyridine with different reagents. The structures of the final products were elucidated by elemental analyses and FTIR, MS, and 1H NMR.