The scientific investigation of biomass combustion strongly relies on the ability of measurement methods to resolve temporal and spatial scales in high-temperature process environments. Specifically, linking generic flames and the physicochemical knowledge gained from them to industrial-scale combustion chambers requires measurement techniques that span a wide range of scales. Tunable diode laser absorption spectroscopy is used as a robust and quantitative measurement method to investigate gas species mole fractions, residence times, and temperature distributions in several combustion systems. Besides different measurement approaches (line-of-sight, 1-D and 2-D) to resolve spatial distributions, this method was enhanced for investigating combustion systems with increasing complexity, including a one-dimensional laboratory-scale gas flame, a single particle combustor, a gas-assisted pulverised biomass combustor, and a semi-industrial scale swirl combustor. Selected results are discussed, which provide validation data for models and numerical simulations.