Electronic phosphorescence and infrared absorption spectra of methylcyanodiacetylene (CH3C5N) are revisited using matrix isolation in solid parahydrogen and neon. Band assignments previously found for Ar, Kr, Xe, and N2 low-temperature host media were updated, with certain ambiguous attributions being resolved. A combined analysis of both dispersed phosphorescence and phosphorescence excitation spectra observed in different environments provides a means to estimate the singlet-triplet separation for the gas-phase and pure solid compound, where phosphorescence could not be observed.