Supercritical fluid reactive deposition is an environmentally friendly technique for the synthesis of supported mono- or bimetallic nanoparticles. Firstly, the present article gives a short introduction into the fundamental aspects of the particle formation process. A critical survey of published knowledge about synthesis of nanostructured materials and their deposition on different kind of supports is given and the underlying process basics i.e. dissolution of the precursor in the supercritical phase, adsorption or sorption of the precursor on the substrate and reduction of the precursor to its metal form are discussed. Examples for successful applications of these supported nanoparticles are highlighted. Based on a critical analysis and evaluation of the current status, strategies for overcoming the knowledge gaps, for essential future research directions are suggested. Throughout the manuscript, the challenges that need to be overcome for an improved understanding of the relationship between process conditions and obtained product properties are stated.