Several imines were synthesized and evaluated as water-initiated hardener for epoxy resin. Imines with a lower electron density on the C=N carbon showed a faster hydrolysis rate. Diethyl ketone-based imines were the most efficiently hydrolyzed among the imines examined, and the adhesive properties of epoxy resin with diimines used as the hardeners were evaluated. A novel diethyl ketone-based diimine, N,N'-di(1-ethylpropylidene)-m-xylylenediamine (10), served as an efficient latent hardener of epoxy resin. Epikote 828 containing 10, filler, and dryer increased the adhesive strength faster than Epikote 828 containing filler and dryer with methyl isobutyl ketone-based imine. The mixed system of epoxy resin and 10 showed good storage stability at room temperature.