In this paper, the results obtained in the last decade by using several electrochemical techniques to characterize species and processes involved in photosynthesis are reviewed, relating them to the work done in this field in our laboratory. The data are discussed in order of increasing level of complexity of the systems to which they are referred, going from chlorophyll aggregates to photosynthetic protein of bacteria and green plants. Possible applications of the photosynthetic systems in the field of the solar energy conversion are also described. (C) 2003 Published by Elsevier B.V.