Development of thermal methods of biomass utilisation is vital for the establishment of bio-refinery technologies. Of such technologies, microwave-assisted pyrolysis is one of the most promising approaches to activate lignocellulose. However, the role of extractives contained within lignocellulose biomass during microwave activation remains unknown. This study investigated how the nature of extractives controls the mechanism of the microwave interaction with lignocellulosic structural components. A general introduction of present and future biorefinery approaches is discussed in Chapter 1. In Chapter 2, the literature review of forest waste extractive, NIR based forest waste characterisation and solvent effect on microwave-assisted cellulose pyrolysis will be discussed. In Chapter 4, the influence of extractive on microwave-assisted pyrolysis of biomass was investigated. The work of Chapter-5 & 6 was focused on the identification of physical-chemical parameters of organic liquid additives. In Chapter 7, the development of a new resonant cavity perturbation (RCP) instrument was discussed. The influence of microwave on Menschutkin-type reaction is highlighted in Chapter-8. Based on obtained experimental results, two novel, fast and inexpensive methods - simultaneous thermogravimetric analysis and near-infrared spectroscopy were shown to be applicable for the identification of the aforementioned lignocellulosic extractives. The multi parameters of complex cellulose-additives interactions in the presence of microwave irradiation were successfully investigated via chemometric methods for the first time.