The embodiments herein provide a HHO generating system and method for generating hydrogen, oxygen and methane. The system adopts electrolysis process to generate a HHO gas from a water-electrolyte solution. The system comprises a reaction tank filled with the water-electrolyte solution, a plurality of disks stacked one above another, a plurality of frames connecting to the disks and an external power supply. The disks comprise a plurality of negatively charged cathode disks and a plurality of positively charged anode disks. The plurality of frames comprises a plurality of conductive frames and a plurality of support frames configured to hold the disks. An electric current is supplied to the conducting frames so as to electrically charge the disks that react with the water-electrolyte solution to produce the HHO gas. The disks are copper-nickel alloy disks in a ratio of 70:30.