English: The image of indium phosphide nanocrystalline surface obtained by electrochemical etching. Microphotograph is made with scanning electronic microscope and coloured with the computer graphic tools by the researchers of Berdyansk State Pedagogical University. . Magnification x10000. At present, various methods for the self-organized formation of nanostructures are actively developing due to their use for the electronic and photon devices, chemical and biochemical sensors [1, 2], etc. In À3Â5 semiconductors for nanostructure formation a rather expensive method of molecularbeam epitaxy or metal-organic vapor-phase epitaxy (MOVPE) is applied. The possible alternative to these methods is the use of electrochemical processes by analogy with the porous silicon production [3]. Feature of the electrochemical process is the low-temperature process, the slight surface damage, the process simplicity and its low cost. Electrochemical methods allow to obtain the high pore density, which is unattainable if use other methods. Indium phosphide monocrystals were produced in the research laboratory of the “Molecular Technology GmbH” Company (Berlin). Thickness of the samples was 1 mm. Plates were cut out perpendicular to the growth axis and polished on both sides. Iodide addition to the fluoride solution essentially influences the pore-formation process. When adding KI (potassium iodide) to 50% etching acid solution, the pore-formation process slows down somewhat, what the currentvoltage characteristics taken during anodization imply about. Morphology of the samples obtained in such solution demonstrates the decrease of the pore inlets (degree of porosity is about 45%). However, the branching of the pore channels under the crystal surface increases. Here the irregular layer preceding the long mutually parallel pores widens up to 2 Pm.