An electronic system based on a microcontroller architecture, devoted to interfacing a three-terminal, ultralow power (ULP) Metal OXide (MOX) gas sensor is presented. The sensor features a novel three-terminal configuration where the microheater is not galvanically isolated with respect to the MOX sensor. The system provides both control of the operating temperature and management of the acquired data. A Pulse Width Modulation (PWM) signal with variable duty cycle is used to provide power to the heating resistor in order to set the desired operating temperature. The heating resistance value is measured in the range (100-300) Ω with a relative error of less than 1%. The circuit devoted to measuring the gas concentration is based on a logarithmic amplifier which measures the current flowing in the sensing layer of the sensor. The measurand range is 30 nA to 60 mA and the relative error of the measured current …