Electrochemical properties of thin films of electroactive materials formed on the electrode surface by the Langmuir-Blodgett (LB) technique are reviewed. The focus is on charge transfer materials which form electroconductive films (tetrathiafulvalene, tetracyanoquinodimethane, fullerenes, phthalocyanines, conjugated polymers etc.) and other LB redox materials such as porphyrins, ferrocenes, metal bipyridine complexes and viologens. Structure-property relationships in experimental voltammetry of LB films and their agreement with theoretical models are examined. Specially organized structures, formed by the LB technique, of different materials for the study of the mechanism of electron transfer and for possible application in molecular electronics are considered as well. Potential applications of the electroactive LB films in electrocatalysis, electrochromic displays, information storage devices and molecular electronic devices are envisaged.