HGH-300 and HGH-500 high purity hydrogen generators are based on the technology of astronautic fuel cells, in which hydrogen is produced by the electrolysis of water, and the produced oxygen is released into the atmosphere. The generator consists of electrolyzing/separating pool, power supply, pressure control, desiccation& purification, flow display etc. The core part -- electrolyzing & separating pool, uses a tube shaped positive pole and a plate shaped negative pole. Both poles are made of stainless steel. The electrolyzing & separating pools store electrolytes, produce hydrogen as well as release hydrogen at the same time. The HGH series hydrogen generators have the advantages of large electrolyzing area, low temperature of the pool, better performance, high production and high purity of hydrogen. The instrument has been specially designed to prevent liquid from back-flowing.