The formation of co-crystals of 2,2'-biphenyl dicarboxylic acid and phenazine is reported, By utilizing different solvents during the crystal preparation, two types of co-crystals, i.e. anhydrous and hydrated, were observed to form. The conformation of the component molecules and the packing arrangement within each co-crystal are described and discussed. In both co-crystals, the generation of a cyclic motif involving one weak (C-H...O) and one strong (O-H...N) hydrogen bonds are observed. Hydrogen bond geometries of the two types of interactions in the cyclic motif for both complexes are reported and discussed.