NOVELTY - The photoelectrolysis cell for producing hydrogen, comprises a photoelectrode, a counter-electrode, an electrolyte in contact with both the photoelectrode and the counter-electrode, and unit for collecting hydrogen produced by the cell. The photoelectrode has a bandgap energy value of 1.5-2.0. The photoelectrode is an anodic of n-type electrode and a cathodic of p-type electrode. The electrolyte is a liquid in which the photoelectrode and the counter-electrode are partially immersed. The liquid electrolyte has a pH greater than 7.    USE - Useful for producing hydrogen by the photoelectrolysis of water using solar radiation.    ADVANTAGE - The photoelectrolysis cell is improved to produce hydrogen in an efficient and an economical manner, and exhibits bandgap characteristics to permit very effective absorption of solar radiation and conversion to hydrogen.    DETAILED DESCRIPTION - The photoelectrolysis cell for producing hydrogen, comprises a photoelectrode, a counter-electrode, an electrolyte in contact with both the photoelectrode and the counter-electrode, and unit for collecting hydrogen produced by the cell. The photoelectrode has a bandgap energy value of 1.5-2.0. The photoelectrode is an anodic of n-type electrode and a cathodic of p-type electrode. The electrolyte is a liquid in which the photoelectrode and the counter-electrode are partially immersed. The liquid electrolyte has a pH greater than 7. The photo electrode has (Ln1-xMx)(Nb1-yTay)O1+xN2-x, where Ln is lanthanide element, M is an alkaline earth metal of calcium, strontium and/or barium, x is 0-0.99 and y is 0-1. The photoelectrode is transparent to the passage of solar radiation. The electrolyte comprises a liquid composition having a pH greater than 7, and a portion of both the anodic electrode and the cathodic counter-electrode are immersed in the liquid composition. The anodic electrode and the cathodic counter-electrode are contacted with each other through a conductor carrying an electrical load, so that an electrical circuit is formed through the cell. INDEPENDENT CLAIMS are included for:    (1) a photoelectrode;    (2) an n-type, anodic photoelectrode;    (3) a method for producing hydrogen in a photoelectrolysis cell; and    (4) a method for carrying out a photoelectrolysis reaction in a photoelectrolysis cell.    DESCRIPTION OF DRAWING(S) - The diagram shows photoelectrolysis device:    Cell; (10)    Photoelectrode; (12)    Counter-electrode; (14)    Electrolyte; (16)    Conventional vessel. (18)