Metallic nanoparticles dispersed on solid surfaces are important for innumerable engineering,scientific and biomedical applications. However, dispersing nanoparticles uniformly over alarge area is a challenge because of agglomeration of nano-particles and not-so-fast kinetics ofmost conventional synthesis processes. In this context, we have presented an ultra-fast, in situmethod for generation of metallic nanoparticles, silver, gold, copper over large surface area ofsolids of different kind: elastomer, paper, fabric and porous gel. In essence, we have usedhydrosilanes for reducing a precursor metal-salt to generate the nano-particles; but unlikeconventional bulk methods, the reaction has been carried out on the rough surface of a poroustemplate. Surface of a porous gel, fibers of paper or fabric materials or any coating present onsuch fibrous materials has been used as this template. In essence our process involves soakingof the substrate with the aqueous solution of the precursor salt and then reduction of the salt bybringing it in contact with a hydrosilane, e.g. one that is used for crosslinkingpoly(dimethylsiloxane) (PDMS) oligomer. In few embodiments, the salt soaked substrate hasbeen brought in contact with PDMS oligomers mixed with the hydrosilane so that reduction ofsalt and crosslinking of PDMS elastomer can occur simultaneously. As a result, the nanoparticles that form get partially embedded into the elastomer surface thereby eliminating anypossibility of agglomeration of nano-particles. In another embodiment, the salt soakedsubstrate is brought in contact with hysrosilane dissolved in a solvent; here reduction reactionoccurs at the roughness pattern of the substrate leading to generation and adsorption of nanoparticles. Rough topography of substrate acts both as the sites for reaction and heterogeneousnucleation of crystals of nano-particles. We have demonstrated the application of these nanoparticles dispersed over a surface by detecting an adsorbed analyte at ultra-low concentrationvia Surface Enhanced Raman Spectroscopy (SERS) and also by making colored optical lensessuitable for microscopy applications.