The administration of gaseous nitric oxide as a biocidal moiety is proffered as a de novo treatment in the control and eradication of biofilms. The present invention relates to the use or methods of application of exogenous nitric oxide gas (gNO) as a stand alone biocidal agent or in cohort with any or all adjunct vehicles in the control of biofilms generated by microbial organisms, i.e., bacteria, protozoa, amoeba, fungi etc. Further, the present invention introduces the concept of utilization and methods of application of gaseous nitric oxide in control and eradication of biofilm forming microorganisms. Noteworthy areas of application are offered as examples. They include, and are not limited to, air and/or water heating/cooling distribution systems in facilities such as hospitals and laboratories, surfaces of medical devices, household surfaces, dental plaque, dental and/or medical water treatment lines, industrial pipelines, water treatment and distribution facilities and fluids sterilization. Various specialized delivery apparatus will be designed to facilitate nitric oxide gas administration to each specific unique application.