This thesis presents, in detail, all the steps of the development of a new in-situ spatially resolved method to probe gas phase concentrations and temperature with minimum invasiveness. From the literature review, it was noted that no techniques developed to date were designed to investigate packed powdered catalyst beds which simultaneously obtain the gas concentrations and the temperature profile. Within this thesis, details of the development of a prototype and further optimisation of a spatial resolution technique for packed powdered catalyst beds were disclosed. The technique was designed to have negligible impact on the packed powdered catalyst bed with the use of the smallest equipment available. Significantly, a number of validation tests of the spatially resolved technique were conducted and the results proved that the technique was working under different experimental conditions. The results of these validation tests highlighted the improvements of the optimised spatial resolution system, which provided twice as many sampling points as the prototype, as well as the additional benefit of simultaneous temperature recording. Additionally, the invasiveness of the spatially resolved technique was investigated using Computational Fluid Dynamics (CFD); more precisely the sampling capillary was found to have negligible impact on the packed catalyst bed during the experiment. Furthermore, the results obtained experimentally have been compared with simulations using a micro kinetic model. The results obtained showed that a hybrid model (simulated concentrations and experimental temperature) allowed a more accurate picture of the phenomena occurring in the packed catalyst bed which was one of the initial aims of the development of the spatially resolved technique.