The Iridium Catalysed Electrolysis CubeSat Thruster (ICE-Cube Thruster) is a novel micro-scale rocket engine which is being developed by URA Thrusters. The thruster utilises the propellants of hydrogen and oxygen produced by the electrolysis of water and is designed to produce a thrust of only 4.5mN. Designing a Micro-Electrical Mechanical Systems (MEMS) thruster to function at this scale is a unique challenge and requires a very different approach compared to the typical rocket engines. Our team conducted a series of parametric studies consisting of geometrical and operational parameters using high-fidelity simulations and obtained critical design data including temperature, pressure and velocity in different parts of the combustion chamber, which enabled the company to successfully improve the design of the thruster. In addition, a bespoke combustion efficiency was developed and a series of reaction equations were implemented by our team in order to enhance the design and obtain the main combustion species.