Hot isostatic pressing (HIP) is a thermal treatment method that is used to consolidate, densify or bond components and materials. Argon gas is commonly used as the pressure medium and is isostatically applied to the material with an excess pressure of 500-2000 bar and a temperature of 500-2200oC. With HIP treatment being a well-established technology for the last decades, one is now striving to obtain an increased understanding of local details in the internal gas flow and heat flux inside the HIP apparatus. The main objective of this work is to assess the potential of using computational fluid dynamics (CFD) as a reliable tool for future HIP development. Two simulations are being performed of which the first one is a steady-state analysis of a phase in the HIP-cycle called sustained state. The second simulation is a transient analysis, aiming to describe the cooling phase in the HIP-cycle. Both of the simulation models have shown to yield satisfactory solutions that is consistent with the reality. With the achieved results, CFD has now been introduced into the HIP field and the presented modeling methods may serve as guidelines for future simulations.