A diode-laser sensor system has been applied to measure the concentrations of NO, N2O, CO, and CO2 in combustion gases using absorption spectroscopy and fast extraction- sampling techniques. Measured survey spectra of the NO 3v band and H2O lines from the v2 + v3 band in the spectral region from 5556 cm-1 to 5572 cm-1 were recorded and compared to calculated spectra to select optimum transitions for NO detection. Similarly, measured survey spectra of the N2O 3v3 band from 6535 cm-1 to 6600 cm-1 were used to identify optimum transitions for N2O detection. High- resolution NO absorption measurements were recorded in a fast-flow multipass cell containing probe-sampled combustion gases to determine NO concentrations in a laminar, premixed CH4/air flame, seeded with NH3. For fuel-lean conditions, the measured No mole fractions corresponded to 68 percent of the injected NH3. For fuel-rich conditions, the fraction of NH3 converted to NO decreased with increasing equivalence ratio. In additional experiments, CO and CO2 absorption measurements were used to determine species concentrations above a laminar, premixed CH4/air flame. Good agrement was found between measured CO and CO2 concentrations and calculated chemical equilibrium values.