The potential applications of nano-antimicrobial materials are well recognised. A large suite of characterisation techniques are available for the study of nano-antimicrobial materials. The choice of technique depends on the material properties in question and the information required. The focus of this chapter is on the surface and interface techniques as these provide information on material activity and efficacy. Antimicrobial properties of a nanomaterial must be characterised in terms of two interrelated aspects. The nature of the chemical and physical properties of the nanomaterial in question must be fully characterised in terms of, i.e. particle morphology and the elemental composition of the particle. Subsequently, it is necessary to characterise the material in terms of antimicrobial potential. This chapter provides a general guide and overview of characterisation techniques available to researchers studying nano-antimicrobial materials, including key microscopic methods, spectroscopic methods, and some physical surface characterisation methods. The chapter identifies how these techniques can be used to study the physical characteristics of the nanomaterials themselves and the antimicrobial effects on the material surface.