NOVELTY - A regenerative photo electrochemical cell comprises photo anode containing semiconductive metal layer(s) on conductive substrate. A second compound is co-adsorbed together with chromophoric substance on semiconductive metal oxide layer. The second compound comprises hydrophobic part and anchoring functional group(s). The conductive substrate is sensitized by chromophoric substance adsorbed on semiconductive metal oxide layer.    USE - As dye sensitive solar cell useful in replacing conventional inorganic photovoltaic devices.    ADVANTAGE - The cell provides long-term stability at at least 80 degrees C. It improves thermo stability of the cells.    DETAILED DESCRIPTION - A regenerative photo electrochemical cell comprises photo anode. The photo anode comprises semiconductive metal layer(s) on a conductive substrate. The conductive substrate is sensitized by chromophoric substance adsorbed on the semiconductive metal oxide layer. The chromophoric substance is ruthenium, osmium or iron complex with ligands, anchoring group(s), counter electrode, transparent or translucent electrode(s), and electrolyte arranged between semiconductive metal oxide layer and counter electrode. The ligands are bidentate, tridentate or polydentate polypyridyl compounds. The electrolyte comprises redox system. The redox system comprises electrochemically active salt and first compound forming redox couple with anion or cation of the electrochemically active salt. A second compound is co-adsorbed together with chromophoric substance on the semiconductive metal oxide layer. The second compound comprises hydrophobic part and anchoring functional group(s). The anchoring functional group(s) is carboxylic acid, phosphoric acid, phosphonic acid, sulfuric acid, sulfonic acid, or their deprotonated forms.    An INDEPENDENT CLAIM is included for chromophoric substance of structure RuLL'(NSC)2.    DESCRIPTION OF DRAWING(S) - The figures show drop in the open circuit potential of device with co-adsorbent 1-decylphosphoric acid during 1000 hours aging of device at 80 degrees C; and relationship between the efficiency of device over time.