Abstract: A microsensor for electrochemical measurements allowing the determination of concentration or concentration profile of at least one chemical compound with small size or molecular weight, under organic, inorganic, neutral or ionic form in an aqueous environment. The microsensor comprises an array (15) of microelectrodes (16), assembled on a chip (10) supported by an isolating substrate (7), and linked with at least one conductor protected by an insulating layer to a contact allowing the connection to a measuring apparatus. The said microsensor is totally coated with an hydrophilic gel (25) which is chemically inert with respect to the chemical compound, is hydrated at a level of at least 70 %, and has a thickness superior to 10 times the size of the microelectrodes (16). And an integrated electrochemical microsystem including the microsensor.