Reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulphosuccinate (AOT) in nonpolar organic solvents are widely known to have very high solubilization power for water. The method is applied to the hydrolysis of p-nitrophenyl acetate (PNPA) catalysed by α-chymotrypsin (α-CT) in AOT/isooctane/buffer RMs. The increase in α-CT activity and stability was an optimum at w o ([H 2 O]/[AOT]) = 10, z [Isooctane]/[AOT]) = 5. Three typical surfactants were selected based on their head group charges: a non-ionic surfactant Triton-X 100 and two zwitterionic sulphobetaine surfactants of the type C n H 2n+1 N + Me 2 (CH 2) 3 SO − 3 (n = 10; SB3-10, n = 16; SB3-16). The kinetic parameters (such as k cat and K M) of the α-CT at 27 • C were determined and compared in the absence and presence of three surfactants. The effect of chain length of zwitterionic surfactant (SB3-10 and SB3-16) on the enzymatic efficacy of α-CT as a function of mixed surfactant addition has been investigated in AOT/isooctane RMs at pH 7.75.