Abstarct: In this work facile synthesis of new derivatives of thiazolo [2,3-c][1,2,4] triazines through palladium-catalyzed heteroannulation is reported. Treatment of 6-methyl-1,2,4-triazine-5-one-3-thione (3-2) with propargyl bromide in sodium methoxide affords 3-propargyl thio- 1,2,4-triazine- 5- one (3-3) in good yield. When compound (3-3) in acetonitrile was reacted with aryl iodides (3-4) and triethylamine in the presence of bis (triphenylphosphine) palladium chloride(II) and cuprous iodide at room temperature, derivatives of thiazolo [2,3-c][1,2,4] triazine (3-5) were obtained in high yields. The reactions were carried out under an argon atmosphere, and the acetonitrile and triethylamine mixture was degassed prior to use. In conclusion the described method for the synthesis of thiazolo triazines heterocycles is an easy and one-pot procedure with good to high yields which can be extended to the synthesis of other heterocyclic compounds.