ESR spectra of Fremy's salt in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles were recorded at high pressures in order to monitor dynamic properties of water molecules inside water pools. Rotational correlation times of Fremy's salt in large AOT water pools slightly decreased with increasing pressure, conversely those in small water pools increased with pressure: Delta V++ for the rotational motion = -1.05 and 9.19 cm(3) mol(-1) at omega(0) = 20 and 2, respectively. These results demonstrate that most water molecules in small water pools are bound to AOT head groups and show very different physical properties from bulk water. (c) 2005 Elsevier B.V. All rights reserved.