Scanning tunneling microscopy (STM) was used to study physisorbed monolayers of 5-octadecyloxyisophthalic acid (C(18)ISA) and 5-[omega-(4’-dodecyloxy-4-azobenzeneoxy)dodecyloxy]isophthalic acid (C-12(AZO)C(12)ISA) at a liquid/graphite interface. The acquired STM images exhibit the molecular packing of the monolayers with submolecular resolution. Monolayers formed by codeposition of solvent molecules and C(18)ISA or C-12(AZO)C-12- ISA molecules are found when 1-octanol and 1-undecanol are used as a solvent. The cis and trans isomers of C-12(AZO)C(12)ISA, the reagent and reaction product of a reversible photoinduced reaction, are simultaneously present and are both structurally identified at the liquid/graphite interface.