The synthesis, structure, and hydrolase-like catalytic activity of a new mononuclear gadolinium complex [Gd(L)(NO3)(H2O)3](NO3)2 (1) are reported. A clean two-stage kinetic reaction for hydrolysis of the diester 2,4-bis(dinitrophenyl)phosphate by 1 was followed, and the rate constants were determined. A high DNA cleavage activity was also demonstrated. The active species in the hydrolytic process is proposed based on the X-ray structure, electrospray ionization mass spectrometry analysis, and kinetic and potentiometric equilibrium studies of 1.