Low-energy electron-energy-loss spectra of solid acetylene were recorded in the range of the low-lying valence excited triplet states at a temperature of 17 K. The spectra show that the first band, which was previously assigned to a single transition, actually contains several overlapping singlet-triplet transitions. The transition (1) Sigma(g)(+) --> (3)A(u) starts with an extrapolated lowest vibronic transition at 4.89 eV and is dominated by the bending vibrational mode with frequency 86 meV (694 cm(-1)). Below this band the spectra show a short progression with vibrational spacings of 100 meV (806 cm(-1)) starting at 4.62 eV and a weak band with irregular vibrational spacings close to the energy-loss threshold. Both are assigned to the transition to the lowest tripler potential energy surface, which correlates to the linear (3) Sigma(u)(+) State and the two bent B-2 and B-u isomer states.