Tropic acid is a 3-hydroxy monocarboxylic acid that is propionic acid in which one of the hydrogens at position 2 is substituted by a phenyl group, and one of the methyl hydrogens is substituted by a hydroxy group. It has a role as a human xenobiotic metabolite. It is functionally related to a propionic acid and a hydratropic acid. It is a conjugate acid of a tropate.