Near-infrared luminescence was observed from cobaltocene molecules doped into single crystals of ruthenocene. The spectrum and lifetime of the luminescence under UV excitation were studied between 6 and 100 K. Below 30 K, the cobaltocene luminescence is weak compared to that of the ruthenocene host lattice but becomes dominant above 50 K, evidence for a thermally induced energy transfer from ruthenocene to cobaltocene. The activation energy is estimated to be 140(40) cm(-1) from luminescence decay curves. Selective excitation revealed the cobaltocene luminescence to be a broad, unstructured but highly asymmetric band with a maximum at 13 100 cm(-1) (760 nm). Comparison with the absorption spectrum determines the energy of the lowest excited state to be 14 050 cm(-1). Calculated luminescence spectra using time-dependent quantum-mechanical calculations demonstrate that the highly asymmetric shape is due to a dynamic Jahn-Teller effect in the ground state along a high-frequency ligand-centered mode. The calculations also show an elongation of the Co-cyclopentadienyl bond length of 0.07 Angstrom in the emitting state.