A magenta azomethine dye(D) was synthesized from the reaction of 3-methyl-1-phenyl-2-pyrazoline-5-one with N,N-diethyl-1,4-phenylenediamine. The magenta azomethine dye was identified on the basis of elemental analysis, $^{13}C-NMR$, infrared, and GC/MS studies. The magenta azomethine dye was decomposed in a basic solution. Rate constants of the fading reaction of magenta azomethine dye in ethanol-water solvent were measured spectrophoto­metrically at 540 nm. Reaction rate was increased with the increase of $[OH^{-}];and;[H\_{2}O]$ in the region of $[H_{2}O]=11~40;M$. The reaction was governed by the following rate law. -d[D]/dt = ${k_o;+;k_{OH}[OH^-][H_{2O}]}[D]$ A possible mechanism consistent with the empirical rate law has been proposed.