Abstract: A method and apparatus for the decomposition of hydrogen peroxide, particularly for use as a hydrocarbon well bore and pipeline cleaning and maintenance aid. The apparatus includes a decomposition engine having an inlet manifold extending centrally within the housing and having means for passage of hydrogen peroxide through the manifold wall through a catalyst stack. The decomposition products produced are directed through an exit venturi. The decomposition products are passed through a piping system which allow the selective venting or introduction of the products into a facility to be cleared. Control means are coupled to the engine and valving to allow for the selective adjustment of temperature and or pressure of the decomposition products, as well as the introduction and diversion of the blend into the facility.