In the title compound, C22H23ClN2O2S, the chlorophenyl ring is inclined to the pyridine ring of the isoquinoline ring system by 79.78 (4)°. The cyclohexane ring adopts a flattened boat conformation. In the crystal, dimers form through complementary sets of inversion-related O—H...O and C—H...O hydrogen bonds. These are connected into zigzag chains along the c-axis direction by pairwise C—H...N interactions that also form inversion dimers.