This study presents a numerical analysis of first and second Law performances of counterflow double-channel micro-combustors. A parametric analysis is conducted to determine the influence of the inlet velocity, the chamber geometry, and the fuel composition on the mean wall temperature, the uniformity of the wall temperature, and the second law characteristics. We show that the double-channel combustor greatly increases the uniformity of the wall compared to the single channel configuration. The oval shaped thread configuration results in the highest wall temperature and the wall temperature uniformity. Increasing inlet velocity results in an increased mean wall temperature and a slightly reduced wall temperature uniformity. The greatest contributor to entropy generation is found to be resulting from chemical reaction. The analysis showed that the second law efficiency was just below 0.5 regardless of the thread shapes. The thread shapes had no major influence on the combustor exergy. A blended ammonia-hydrogen fuel is shown to be resulted in a slightly higher mean wall temperature and a less uniform wall temperature.