The components of a 4:1 mixture of Rh(III)Cl tetrakis(4-methylphenyl)porphyrin 1 and a bowl-shaped tetra(4-pyridyl)cavitand 4 self-assemble into a 4:1 complex, 1(4)center dot 4 via Rh-pyridyl axial coordination bonds. The single crystal X-ray diffraction analysis and variable-temperature (VT) H-1 NMR study of 1(4)center dot 4 indicated that 1(4)center dot 4 behaves as a quadruple interlocking gear with an inner space; wherein (i) four subunits-1 are gear wheels and four p-pyridyl groups in subunit-4 are axes of gear wheels; (ii) one subunit-1 and two adjacent subunits-1 interlock with one another cooperatively, and (iii) four subunits-1 in 1(4)center dot 4 rotate quickly at 298 K on the NMR. time scale. Together, the extremely strong porphyrin-Rh-pyridyl axial coordination bond, the rigidity of the methylene-bridge cavitand as a scaffold of the pyridyl axes, and the cruciform arrangement of the interdigitating p-tolyl groups as the teeth moiety of the gear wheels in the assembling 1(4)-unit make 1(4)center dot 4 function as a quadruple interlocking gear in solution. The gear function of 1(4)center dot 4 was also supported by the rotation behaviors of other 4:1 complexes: 2(4)center dot 4 and 3(4)center dot 4 obtained from Rh(III)Cl tetrakis[4-(4-methylphenyl)phenyl]porphyrin 2 or Rh(III)Cl tetrakis(3,5-dialkoxyphenyl)porphyrin 3 and 4 also served as quadruple interlocking gears, whereas 1(4)center dot 5 obtained from 1 and tetrakis[4-(4-pyridyl)phenyl]cavitand 5 did not behave as a gear. The results of activation parameters (Delta H double dagger, Delta S double dagger, and Delta G double dagger) obtained from Eyring plots based on line-shape analysis of the VT H-1 NMR spectra of 1(4)center dot 4, 2(4)center dot 4, and 3(4)center dot 4 also support the interlocking rotation (geared coupled rotation) mechanism.