An absorption spectrometer utilizing a tunable distributed feedback diode laser at 2.3 μm and an interband cascade laser at 3.1 μm has been developed to measure temperature and concentrations of CO, CH4, C2H2, and H2O under gasification conditions. A wavelength division multiplexing approach using a single ZrF4-fiber was used to measure both wavelength regions simultaneously. The performance of the spectrometer has been tested in laminar flat flames and a heated cell and then applied for measurements at an atmospheric entrained flow gasifier (REGA). A water-cooled optical probe was used to provide optical access at two measurement positions. By moving the burner, axial profiles of temperature and species concentration could be obtained. These profiles were compared with numerical simulations and can be used to validate the simulation.