Abstract <p>The present work deals with synthesis, characterization and <i>in vitro</i> reactivation of chlorpyrifos inhibited acetylcholinesterase by 3-[(1<i>E</i>,14<i>Z</i>)-3-(4-aryl)-3-(hydroxyimino)prop-1-enyl]-1-methylquinolin-2(1<i>H</i>)-one derivatives. Synthetic strategy involving the condensation of 1,2-dihydro-1-methyl-2-oxoquinoline-3-carbaldehydewith substituted acetophenones in presence of piperidine and ethanol as a solvent afford a series of chalcones with good yield. The title compounds were prepared by the condensation of the chalcones with hydroxylamine hydrochloride in ethanol and pyridine as a base. The structures of all the newly synthesized products were confirmed with their elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral analysis. All the newly synthesized compounds were screened for their reactivation efficacy against chlorpyrifos inhibited electric eel AChE by Ellman’s method. The data reveal that all the newly developed reactivators could not reactivate chlorpyrifos-inhibited AChE. Only two compounds of chalcone oxime, <i>p</i>-amino and <i>p</i>-nitro were found to be moderate reactivators as compared to standard.</p>