Abstarct: Among a large variety of N-containing heterocyclic compounds, those containing hydrazine moiety as 'fusion site' have received considerable attention because of their pharmacological properties and clinical applications. An efficient practical approach to triazolo[1,2-a]indazole-1,3,8-triones from urazole, dimedone, and aldehydes was developed that uses nanoboehmite - phosphoric acid as a green catalyst in a solvent-free one-pot three-component cyclocondensation reaction. This method should provide good yields, a shorter reaction time, an easy work-up, purification of products by the non-chromatographic method, and a cleaner reaction.