A clean and straightforward methodology developed for the synthesis of substituted indazoles using silica supported polyphosphoric acid (PPA-SiO2) catalyzed condensation reaction between substituted 2-hydroxybenzaldehydes or acetophenones and hydrazine hydrate or phenylhydrazine. The reaction conditions are optimized for different solvents at different temperatures. The yield of the products improved to 88 to 90 % using silica supported polyphosphoric acid as a catalyst, which is reusable, cost-effective and straightforward to synthesize.