In this study a phase transition in H2O due to an applied very high local electric field E at ambient conditions is predicted. We analyse the equation of state and behaviour of entropy. For E = 10(9) V m(-1) some characteristic features of local electrostriction pressure Pi and of entropy change DeltaS as a function of the field strength E are noted. These features are interpreted as testifying to a phase transition: water in low field --> H2O in high field (or, in other words, H2O compressed by the field). A consistency of the present results with recent off-specular surface X-ray scattering studies is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.