The formation of scale on heat transfer surfaces during pool boiling is a frequent engineering problem where aqueous solutions are involved. In this investigation the effect of modified surfaces on deposition of calcium sulfate on heat transfer surfaces was studied. The surfaces were either implanted with ions such as F: Si, and ii using range-matched implants, or sputtered with diamond-like carbon, TaC, and TaC-F using a closed-field magnetron ion sputtering system. Fouling runs during pool boiling of CaSO4 were carried out with varied heat fluxes and two different salt concentrations. The results showed that these modifications of the heat transfer surfaces mitigated fouling significantly.