Abstract: A simple, efficient and green approach to the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones has been developed via one-pot three-component reaction of aromatic aldehyde, malononitrile and phthalhydrazide catalyzed by zinc-proline complex (Zn[L-proline]2) using H2O: PEG400 = 6: 4 as solvent. Atom economy, good to excellent yield, operational simplicity and easy workup are important features of this method. Graphical abstract: [graphic not available: see fulltext]