The polyurethane (PU)/polyaniline (PANI) IPN, at three composition ratios (95/05, 75/25, 60/40), were analyzed, after the action of the urease enzyme, by means of the Hyperchem 8v software. Theoretical analysis of Gibbs free energy, FTIR, and 13C-NMR were done. The generation of functional groups due to hydrolysis was analyzed by FTIR. The 13C-NMR spectra of the three ratios showed a superposition of the individual spectra of PU and PANI and an appreciable decrease of the signals due to the action of the urease enzyme. The orbits showed that the electron density of the HOMO (Highest Occupied Molecular Orbital) is predominantly localized on the C-C bond, indicating that the binding of PU/PANI with the urease enzyme contains a vacant d-orbital. It is concluded that the adsorption of the urease enzyme increases the degree of hydrolysis of the IPN.