The need to determine the surface area of materials is well established; it influences many aspects of product performance. The most widely employed technique is that of (BET) gas adsorption but it is only useful for analyzing dry powders. However, the overwhelming majority of manufactured products, including nanoparticulate systems, involve suspensions of particulate materials in some fluid, either in the final state or at some stage of their production. Gas adsorption is not well suited to such systems; drying takes time and will promote aggregation. We describe a revolutionary instrument designed to measure the surface area of nanoscale particles or droplets dispersed in a liquid. This new (patent pending) technique is based on nuclear magnetic resonance (NMR) and it offers many advantages in comparison with conventional surface area instrumentation. The technique is based on the fact that liquid in contact with, or “bound” to, the surface of a particle behaves differently from that of the bulk or “free” liquid. The NMR relaxation time of bound versus bulk liquid is markedly different: the relaxation time of the latter is much longer. No assumptions need to be made about the sample particle (distribution) or shape in the determination of the surface area; it is measured directly. Suspensions and emulsions can be measured non-invasively, without dilution. The upper limit in concentration is essentially unlimited; the lower limit is about 1-2%. The theory underpinning this new approach to surface area measurement will be discussed and examples given to illustrate its wide applicability.