A new composition of a fully water-dilutable microemulsion system stabilized by natural surfactants is presented as a template for preparation of celecoxib nanoparticles. Nanoparticles are obtained as a dry powder upon rapid conversion of microemulsion droplets with dissolved celecoxib into nanoparticles, followed by evaporation of all the liquid in a spray dryer. The resultant powder is easily re-dispersible in water to form a clear, transparent dispersion. The celecoxib nanoparticles are amorphous and their average size in the dispersion is 17 nm, in agreement with cryo-TEM results and concentration measurements after filtration. As a result of the nanometric size and amorphous state, about 10-fold increase in dissolution of the powder was obtained, compared to that for particulate celecoxib in the presence of surfactants.