A method is suggested to characterize the defect density of a given gallium nitride film, through anodic etching. We report that oxalic acid etches gallium nitride, at room temperature and pressure in an electrolytic cell. Etching is theorized to proceed by attacking those points where planar defects and threading dislocations terminate on the GaN surface. The effect of varying electrolysis voltage on the etch pit density of the porous gallium nitride thus formed is investigated. Etch pit densities on the order of 4 x 10(10) pits/cm(2) were measured. The use of etch pit density to estimate defect density of a given GaN film is discussed.