Space radiation is significantly harmful to electronic Components. The operating time, duration and orbit of the space mission are affected by the characteristic of the radiation environment. The aging and the performance of the electronic components are modified by radiation. The performance of the space systems such as electronic units, sensors, power and power subsystem units, batteries, payload equipments, communication units, remote sensing instruments, data handling units, externally located units, and propulsion subsystem units is determined by the properly functioning of various electronic systems. Such systems are highly sensitive against space radiation. The space radiation can cause damage to electronic components or functional failure on the electronics. A precisely methodology is needed to ensure that space radiation is not a threat on the functionality and performance of the electronics during their operational lives. This methodology is called as &rdquo / Radiation Hardness Assurance&rdquo / . In this thesis, the hardening of electronics against space radiation is discussed. This thesis describes the space radiation environments, physical mechanisms, effects of space radiation, models of the space radiation environment, simulation of the Total Ionizing Dose, and &rdquo / Radiation Hardness Assurance&rdquo / which covers Total Ionizing Dose and Single Event Effects testing and analyzing of the electronics.