The objective of this work is to outline a new coating technology suitable for surface modification with ion beams. The aim is to develop well-adherent, cohesive coatings from nano-particles deposited on metal surfaces. Previously, ion-beam burnishing of graphite deposited from colloidal suspensions has been reported. Today, nano-particles of diamond, as well as of a number of chemical compounds used for hard coatings (SiC, ZrO 2 and Al 2O 3), are commercially available with typical particle sizes in the range 4–300 nm. A coating of nano-particles on a substrate surface may, in principle, be modified with high-energy ion beams. However, deposition of nano-particle coatings on metals is difficult due to agglomeration during the deposition process, and this may result in air-filled cavities in the powder coatings. In this situation, even ion bombardment cannot improve the cohesion of the powder coating nor ensure sufficient adhesion to the substrate. In this paper, two main methods for depositing nano-particles as coatings on metal surfaces are discussed. For instance, slurries of nano-particles may be collected on an electrode in an electrophoresis cell. In addition, slurries or solutions may be electrosprayed through the hollow needle of a hypodermic syringe at a potential of 6–8000 V, and this will produce a uniform spray of submicrometre droplets. This technique is discussed in more detail, particularly with respect to the formation of sub-micrometre droplets containing only a few nano-particles which dry before deposition on the grounded substrate. We report the development of uniform coatings of nano-particles on metals and discuss the surface modification of such coatings by ion beams as an alternative method to vacuum deposition processes, which causes no extensive interfacial stresses as, for example, in PVD processes. The tribological applications of coatings of ion-bombarded nano-particles are highlighted, with particular emphasis on the low-friction surfaces obtained by the deposition of nano-particles from colloids of graphite. The effect of ion bombardment is investigated by following the time dependence of the friction coefficient, using a reciprocating ball-on-disc tribometer. Nano-particles have not previously found technological applications using surface modification by ion beams. With the availability of commercial products and the development of new deposition methods, a new type of interface engineering may result. It may be possible to bombard nano-particle coatings with ions prior to conventional PVD to yield a nano-composite material which can act as a residual stress reliever. In this paper, we report examples of ion-beam-modified coatings of nano-particles which result in an improvement of the friction, wear and corrosion of metal surfaces. We also discuss the use of nano-particle coatings deposited from solutions of fullerenes or “bucky balls” in toluene or benzene.