The kinetics of oxidation of hexamine by quinoliniumdichromate (QDC) has been investigated spectrophotometrically in aqueous perchloric acid medium at constant ionic strength. The reaction is first order with respect to oxidant and reductant. Increase in perchloric acid concentration increases the reaction rate and order with respect to acid concentration is nearly two. The added products chromium(III), formaldehyde and oxime do not have any significant effect on the rate of reaction. Increase in ionic strength and decrease in dielectric constant of the reaction medium increases the rate of reaction. A suitable mechanism is proposed and the constants involved have been obtained. The activation parameters were evaluated with respect to slow step of the mechanism and discussed.