The electrochemical active area of porous LiCoO2 electrode in 1 M LiClO4 propylene carbonate (PC) solution was determined from the lithium ion diffusivity measured by means of the galvanostatic intermittent titration technique (GITT). The measured electrochemical active area is clearly reduced with increasing lithium content (1 - delta). (C) 1998 Elsevier Science B.V. All rights reserved.