Software and hardware advancements on a hydroxy gas (HHO) production system is presented in this experimental study. A unique control system that enables to generate hydroxy gas at the specified volumetric flow rates with pulse width modulation (PWM) technique is developed and manufactured. The novelty of the method is automatic control of the hydroxy production according to the instantaneous demand, in other words, the adaptation of the HHO system to the operating principles of internal combustion engines (ICEs). A stepping motor represented the vehicle engine in order to get variable rotational speed values. The instantaneous rotation speed range of the motor divided into four sections as no rotation, low (1000-2001 rpm), middle (2001-4001 rpm) and high (>4001 rpm). A computer-driven microcontroller (MCU) card managed the entire system. The MCU card received motor speed input parameters and identified the PWM signal. Results of the study which are the electrical current, hydroxy gas flow and dry cell temperature ranges are presented in tables and graphs. The measured experimental data were 0-15 A, 0-1.56 L per minute and 24-48 degrees C for electrical current, hydroxy gas production and dry cell temperature ranges, respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.