Dynamic quenching of luminescence of tris(2,2’-bipyridyl)ruthenium(II) chloride by potassium hexacyanoferrate(III) in the sodium bis(2-ethylhexyl) sulfo succinate (AOT)/water/heptane reversed micellar system was studied as a function of pressure from 0.1 to 300 MPa at 25 degrees C. From the analysis of the decay curves in solutions with W-0 (=[H2O]/[AOT]) of 10.3, 14.0, and 22.0, it was found that the quenching rate constants, k(q), in micelles were decreased significantly with increasing pressure, while the rate constants, k(ex), for the quencher exchange by collision between micelles were found to increase strongly with increasing pressure. The activation volumes for k(q) were almost independent of W-0 (16 cm(3)/mol), and those for k(ex) were decreased monotonically from -24 (W-0=10.3) to -54 cm(3)/mol (W-0=22.0) depending on W-0. From the results of the pressure dependence of k(q), the microenvironment inside the micelles is discussed. The largely negative activation volumes for k(ex) are interpreted on the basis of an encounter or a collision complex formation between micelles prior to the quencher exchange, whose dissociative backward process exhibits larger pressure dependence than the forward one.