NOVELTY - A method for producing oxygen from water involves subjecting water to electrolysis to produce hydrogen and oxygen; drying the produced oxygen using air as a drying agent; flowing a stream of produced H2 to the anode side of the fuel cell to react with oxygen in the agent air to produce water, electrical energy and heat; and using electrical energy produced by the fuel cell in the electrolysis.    USE - The method is for producing oxygen from water and the produced O2 is supplied to a human respiratory system (claimed).    ADVANTAGE - The inventive method utilizes a lightweight, quiet, inexpensive device that can generate pure oxygen in quantities small enough to be cost effective for single patient use.    DETAILED DESCRIPTION - Production of oxygen (O2) from water comprises:    (1) subjecting water to electrolysis to produce hydrogen (H2) and O2;    (2) returning H2 to a water storage zone;    (3) drying the produced O2 using air as a drying agent;    (4) flowing a stream of air to cathode side of a fuel cell;    (5) flowing a stream of produced H2 to the anode side of the fuel cell to react with O2 in the agent air to produce water, electrical energy and heat; and    (6) using electrical energy produced by the fuel cell in the electrolysis.    An INDEPENDENT CLAIM is also included for a piece of apparatus for producing O2 from water, comprising an electrolyzer, water storage zone, gas dryer, fuel cell, air stream removing element, and mechanisms for supplying electrical energy produced by the fuel cell to the electrolyzer. The gas dryer receives the produced O2 and a stream of air. The fuel cell has a cathode side connected with the dryer to receive drying agent air. It also has an anode side connected with the electrolyzer to receive produced H2, for reaction in the fuel cell with O2 in the drying agent air, to produce water, electrical energy and heat.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram of the inventive system and/or method.