jats:titleAbstract</jats:title>jats:pOzone simulated in Mars Global Climate Models (MGCMs) is used to assess the underlying chemistry occurring in the atmosphere. Currently, ozone total column abundance (TCA) is under‐predicted in MGCMs by up to 120%, implying missing or inaccurate chemistry in models. Heterogeneous reactions of hydroxyl radicals (HOjats:subX</jats:sub>) have been offered as an explanation for some of this bias, because they cause ozone to increase at locations where it's currently under‐predicted. We use four simulations to compare modeled ozone TCA with observations from the UVIS spectrometer aboard the ExoMars Trace Gas Orbiter to improve the representation of heterogeneous processes and their impact on ozone. We use a gas‐phase only run, a dissociative scheme, an adsorbed HOjats:subX</jats:sub> retention scheme, and a hybrid scheme that combines the dissociative mechanism with the retention of HOjats:subX</jats:sub> on water ice. We find retention of HOjats:subX</jats:sub> is dependent on water ice sublimation, and ozone abundance increases when water ice persists for longer periods (1–20 sols). Over time, the loss of HOjats:subX</jats:sub> causes a depletion in Hjats:sub2</jats:sub>Ojats:sub2</jats:sub> concentration (HOjats:subX</jats:sub> reservoir), and thus allows ozone concentration to increase. When adsorbed HOjats:subX</jats:sub> are desorbed and dissociate into other by‐products, HOjats:subX</jats:sub> are not immediately available to destroy ozone. This results in larger ozone concentrations than if desorbed HOjats:subX</jats:sub> are released directly back into their gaseous states. When using the hybrid scheme, ozone TCA is increased up to 50% where the ozone deficit is greatest, demonstrating the best agreement with observations, and implying that HOjats:subX</jats:sub> radicals are both retained when adsorbed and dissociate.</jats:p>