Hydrogen isclassified as New Energy and also considered as the most promising transportation fuel candidate in the future. Various pilots test of hydrogen fuel cell vehicles by the world's leading automotive industries since the last 50 years have begun to show bright spot in the utilization of hydrogen-based fuel cells as vehicle fuel. The electrolysis process of water (H2O) would produce H2 (hydrogen) and O2 (oxygen). The conventional method resulted in inconsistent volume and quality of HHO gas. However, the current development of HHO gas production through electrolysis process varies in term of materials, production process, design of certain tools, and technical modifications to obtain optimum results. In this research, the Hybrid Multistack TypeHHO generator has been designed and developed by combining two types of dry and wet cell generators. In this study using both cell type generator (wet and dry cell) or called as a hybrid type. Through the process of electrolysis in HHO enclosure space, the HHO gas was produced. The volume of HHO gas obtained from the HHO generator as an alternative fuel is strongly influenced by the electrical current supplied and the concentration of KOH catalyst used. The test was conducted with four stages of catalyst amount from 5.6g/L; 11.2g/L; 16.8g/L; and 22.4g/L. The applied current is linearly increased, with the increasing HHO gas production. It is proven when with the amount of catalyst used at 22.4g/L, the average HHO gas produced is 230.3mL/min. The author analyzes the performance of the generator in term of current and HHO gas production at a predetermined 12V constant voltage.