The compound LLPNP crystallizes in orthorhombic system, P21 21 21 space group with four molecules in the asymmetric unit. The crystal data for LLPNP is tabled. The lysine molecule (C1-C6/N1/N2/O1/O2) is protonated while the paranitrophenol molecule is deprotonated (C7-C12/N3/O3/O4/O5). The paranitrophenol moiety makes a dihedral angle of 85.87 (9)° with the lysine moiety which shows that they are almost orthogonal to each other. The phenyl ring adopts a planar conformation with C7 atom having a maximum deviation of 0.0013 (14) Å. The oxygen atom O3 attached with the phenyl ring deviates by 0.0004 (1) Å. The nitro group (N3/O4/O5) makes a dihedral angle of 2.63 (1)° with the phenyl ring to which it is attached.