Regular nanostructures are formed by chemical reaction of ammonia gas with crystalline substituted benzoic acid such as p-bromobenzoic (la), p-toluic (Ib), p-aminobenzoic (Ic), and p-nitrobenzoic acid (Id). Their size and shape are determined and depicted by atomic force microscopy (AFM). AFM reveals that the crystal main face (100) of la, (100) of Ib, (100) of Ic, and (001) of Id exhibits craters and volcanoes, craters and volcanoes, volcanoes, and volcanoes, respectively, whereas the long side face (100) of Id gives rise to craters and volcanoes. All the experimental results are correlated with the crystal structures. Molecular interpretations of the AFM features of la, Ib, Ic, and Id are given.