A convenient and versatile synthetic approach to substituted 1, 3-oxazolo [4, 5-d] pyridazinones is developed. The oxazole ring was formed upon reaction of 5-amino-4- hydroxy-3 (2H)-pyridazinone with various carboxylic acid derivatives using a microwave- assisted procedure, which favors the reaction time and purity of the resulting products. The developed methodology is suitable for rapid, parallel, automated synthesis of ...