<p>Photocatalysis is a potent, advanced oxidation process that is effective in converting hazardous organic contaminants into non-toxic end products, offering a sustainable solution for water and air purification. The degradation process in photocatalysis is primarily influenced by several critical factors, including the illumination source, catalyst (either in the form of a slurry or immobilized), the pH range, and reactor design. Numerous costly, time-consuming, and difficult-to-perform experiment trials are conducted in the laboratory to optimize these operating parameters. Computational fluid dynamics (CFD) can be used to surpass these limitations. CFD has several advantages compared to experimentation, such as the capability to conduct many simulations, efficient use of time, cost-effectiveness, and the ability to simulate challenging conditions (such as high temperature, high pressure, or hazardous environments) in various reactor designs. Furthermore, CFD enables the analysis of spatial and temporal variation in independent variables, including velocity variation, reactant concentrations, and light intensity, which provides insights into the reactor. CFD is a popular tool in the field of reactor design and optimization. Its applications include the analysis of flow patterns, the modelling of mass transfer phenomena, and the scaling up of reactor systems to provide efficient designs. This review aims to provide insight into the basic photocatalytic process, the correlation between the photoreactor concept, reaction kinetics, irradiation scenarios (irradiation modelling) and the photocatalytic process parameters (pollution degradation conditions, pollutant type and concentration, different hydrodynamic modelling).</p> Graphical Abstract <p></p>