The title compound, C₉H₈N₂, presents two almost identical independent molecules in the asymmetric unit, both of them exhibiting an extremely planar isoquinoline core (maximum r.m.s. deviation = 0.014 Å). The most significant deviation is found in the -NH₂ groups, which present a noticeable pyramidalization around the N atom, a feature also present in related structures containing the molecule as a ligand. The supramolecular structure is based on pairs of parallel hydrogen-bonded chains formed by just one molecular type each, defined by the strongest hydrogen bonds in the structure, which are of the N–H⋯N type. These parallel chains are linked into pairs (or strips) via weaker C–H⋯N hydrogen bonds. Related strips generated by the c-glide plane define two families running along [10] and [110], giving rise to an interesting system of interwoven chains stabilized by a number of weaker contacts of the C–H⋯π type.