The kinetics of the reaction between 1,3-dinitrobenzene (m-DNB) and acetophenone in presence of OH- ion has been studied in aqueous ethanol medium with equimolar concentrations of OH- and acetophenone (in the range 10-4 to 10-3 mol dm-3) and an excess of m-DNB (∼5 × 10-2 mol dm-3). At such concentrations the reaction has been shown to be of second order (first order with respect to each of OH- and acetophenone). The final product, p-[1-benzoyl-1′-(2,4-dinitrophenyl)methane] has been isolated and characterised. In the reaction medium it forms a purple coloured 1:1 molecular complex with m-DNB and it is the variation of absorbance of this complex with time which has been followed spectrophotometrically during the course of the reaction.