Although usually neglected in aerodynamics, radiation can present the main heat transfer mechanism in some aerodynamic applications and cause significant changes in the behaviour of the flow. Such applications typically include very high-temperature conditions such as hypersonic flow during reentry and hot gas in combustion systems. In these cases, radiative heat transfer must be properly accounted for and the divergence of the radiative heat flux must be added as a source term to the energy budget of the flow. To solve the radiative transfer equation, in this thesis work, use is made of the emission reciprocity based Monte Carlo formulation. To generate spectra, for combustion problems, a routine utilising the High-Resolution Transmission Molecular Absorption database was written. For hypersonic problems, NASA’s NEQAIR was adjusted and implemented. The radiation solver was further coupled with INCA CFD and validated using 14 different simulation cases. Several techniques of solution acceleration were also proposed and tested to reduce the computational requirements of the developed solver, including smart spectral discretisation methods and the use of a multilayered grid separating the radiative and spectral solutions.