We have measured the rate of hydrolysis of t-amylchloride in the solvent, isobutyric acid + water, prepared at its consolute composition. The consolute temperature of the mixture depends upon the initial amount of t-amylchloride, being 32.3 degrees C when 100 mu l are added to 25 ml of the solvent and 36.46 degrees C when 150 mu l are added. In both cases, however, we found that the specific rate of reaction is suppressed over a temperature range of about 0.2 degrees C on either side of the local consolute temperature, T-c. These observations serve to demonstrate the concept of ＇critical slowing down＇ in chemical kinetics. The decrease in specific rate with temperature, T, could be fitted by \T - T-c\(-x) with x = 0.63 +/- 0.28. Within the experimental error, this value of the exponent is consistent with the value (x = 0.80) predicted theoretically on the basis of the principle of universality. (C) 1998 Elsevier Science B.V. All rights reserved.