The cubic modification of the wide band-gap (Eg≈3.4eV) ternary semiconductor α-ZnAl2S4 belongs to the normal spinel structure without cationic disordering. In our previous papers [1 and ref. therein] the optical properties of the chromium doped α-ZnAl2S4 have been examined over a wide temperature range. It was shown, that the Cr3+ ions located in the octahedral sites of the host crystal exhibit a very strong luminescence (even at 540K) the intensity of which increases with temperature. Recently we have also reported the radiative properties of the α-ZnAl2S4 compound doped with Tiions [2]. The emission bands observed for the α-ZnAl2S4:Ti crystals were assigned to ligand - Ti4+ charge transfer with titanium being in octahedral sites. However, in our previous work we did not test the possibility of application of the α-ZnAl2S4:Cr and α-ZnAl2S4:Ti systems as laser media. The aim of the present work is the investigation of the spectroscopic characteristics of the α-ZnAl2S4 single crystals doped with cobalt and vanadium. Along with this for the first time the α-ZnAl2S4:Cr, Ti, Co, V crystals are examined from the point of view of their application as active media for IR solid state lasers. Bulk single crystals of α-ZnA12S4 doped with transition metals were grown by a closed tube vapor method with iodine as a transport agent. The samples with an estimated impurity concentration in the range of 0.1-0.5 at % were optically homogeneous octahedra with dimensions up to 30mm3 and (111) oriented mirror like faces. The X-ray diffraction measurements confirmed that the samples crystallized in the spinel structure with Oh (Fd3m) symmetry. The steady-state and time-resolved photoluminescence (PL) studies, as well as the optical absorption and PL excitation spectra measurements, were carried out at temperatures T=10-300K in the wavelength range 0.4-1.7μm. A photomultiplier and liquid nitrogen cooled germanium, or InGaAs cells were used as detectors. The resonant optical excitation of the transition metal ions (within the absorption bands of the samples) was provided by the emission from gaseous, solid state and dye lasers, as well as from OPO. The PL kinetics has been examined under pulsed excitation with temporal resolution ~10-8s. The EPR studies of the samples have been carried out as well. The observed emission band of the α-ZnA12S4:Co crystals with the maximum at λmax=0.95μm (300K) corresponds to electron transitions of the Co2+-ions in the tetrahedral coordination with Td local symmetry. As in other sulfurous compounds the absorption bands have been attributed to the transition from the ground 4A2g(4F) state to the excited 4T1g(4P), whereas the emission spectra, especially the set of the narrow lines observed at low temperature, can be assigned to the transitions between the excited levels 4T1g(4P)→ 4T2g(4F). The absorption and emission spectra (λmax=1.35μm, 300K) of the α-ZnA12S4:V samples are assigned to electron transitions of V3+ ions surrounded by 6 sulfur atoms. As in the case of Cr3+ ions the luminescence, arising from the vanadium impurity in the α-ZnA12S4 host, becomes stronger as the temperature increases. Taking into account the spectroscopic characteristics and temperature behavior of the optical bands the single configuration coordinate diagrams are constructed for the α-ZnA12S4:Ti, Cr, V, Co crystals. It has been demonstrated that the α-ZnA12S4:Cr crystals in the 0.7-0.9μm wavelength range and the α-ZnA12S4:V crystals in the 1.2-1.6μm range are the most appropriate for application as active media of tunable solid state lasers .