A new class of pyrazolonederivatives has been isolated in good to excellent yields from the 2:1 condensation reaction between 3‐methyl‐1‐phenyl‐5‐pyrazolone and arylaldehydes in the presence of ionicliquid [HMIM]HSO4. The compounds were characterised by their IR, NMR spectra, MS and elemental analyses. The important features of the methodology are a wide application range of substrates, higher yields