In the crystal structure of the ammonium carboxyl-ate-boric acid cocrystal, (C(3)H(7))(4)N(+)·CH(3)CO(2) (-)·H(3)BO(3), the boric acid forms two O-H⋯O hydrogen bonds to the acetate anion. The acetate-boric acid species is hydrogen bonded to another acetate-boric acid species through the third OH unit of the boric acid about a twofold rotation axis.