Disinfectant efficacy is demonstrated through performance testing to show that the disinfectant is capable of reducing the microbial bioburden in either suspension (planktonic state) or from cleanroom surfaces to an acceptable level. Of the different efficacy studies performed by end users for the purpose of disinfectant validation, surface studies are generally regarded as the most challenging but most representative of actual cleanroom conditions. This presentation will focus on the efficacy test requirements for the validation of disinfecting surfaces with mechanical action and aid in determining study parameters suitable to end user application. Factors that should be considered prior to any testing being performed will be discussed, alongside critical review of standardized methods currently available where further development is required to ensure validation approach is reflective of the specific manner in which a disinfectant is used.