TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The electrode base material is an electroconductive clear glass base material, metallic substrate or carbon group base material.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The p-type organic semiconductor is macrocyclic ligand compound or its metal complex, preferably chosen from phthalocyanine derivative, naphthalocyanine derivative and/or porphyrin derivative. The n-type organic semiconductor is polycyclic aromatic compound, preferably chosen from fullerene, carbon nanotubes, conductive polymer doped with electron donor, perylene derivative and/or naphthalene derivative.Preferred Process: An anode is formed by providing a coating layer (I) of n-type semiconductor and a coating layer (II) of p-type semiconductor on electrode base material, sequentially. A cathode is formed by providing a coating layer (I) of p-type semiconductor and a coating layer (II) of n-type semiconductor on electrode base material, sequentially. Transition metal catalyst carrier is optionally added to the layer (II) of anode and cathode. The anode and cathode are connected to the constant potential power supply and immersed in the electrolyte aqueous solution. A voltage of 0.3-1.2 V or 1-1.4 V is applied between the electrodes. The light irradiated on the electrodes is natural light. Oxygen is generated from anode and hydrogen is generated from cathode.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Material: The electrode base material is an electroconductive clear glass base material, metallic substrate or carbon group base material. EXAMPLE - An indium-titanium oxide coated glass substrate was coated with 3,4,9,10-perylene tetracarboxyl bis-benzimidazole and cobalt phthalocyanine to a thickness of 250-350 nm and 135-145 nm, respectively. An organic photocatalyst element was produced. A conducting wire was attached on the photocatalyst element using an epoxy adhesive to form an organic photocatalyst derived electrode. A photocatalytic reaction cell was produced using silver/silver chloride counter electrode and photocatalyst derived electrode (working electrode). Potassium hydroxide or sodium hydroxide having pH of 11 was taken as electrolysis solution. Natural light was used as light source. Electrolysis of water was carried out with the light irradiation amount of 58-60 mW/cm2. Decomposition of water was carried out at 36degreesC and normal pressure with bias potential application of 0.4 V. Oxygen of 1.5 mul/hour was generated as oxidation product and hydrogen of 3.5 mul/hour was generated as reduction product.