Concerns about the environmental impacts associated with using fossil fuels are ever increasing, with a particular focus on the global climate change that is caused by increasing concentrations of greenhouses gases (CO2 among others). Biogas production is a key technology in the development of sustainable energy supply systems that aims to cover the energy demand using renewable sources and to mitigate greenhouse gas emissions. Biogas production can be achieved through anaerobic digestion (AD), a biological process, which uses biomass as a renewable energy source. Pre-treatment is the first stage of the AD process. The main goal of pre-treatment is to change the biomass properties in order to prepare lignocelluloses for enzymatic attack; which in turn enhances biogas production and anaerobic digestion performance. In this work beating treatment as a new mechanical treatment was applied to grass silage to improve the anaerobic digestion combined with sludge to produce biogas. One of the objectives is to investigate the effect of beating treatment on the AD process to produce biogas from grass silage. The other objective is to optimise the condition of the process and develop a mathematical model of this process. Techniques such as Design of Experiment (DOE) and Response Surface Methodology (RSM) have been used to optimise the mean factors of the process (temperature and the time of beating). A Bioreactor has been designed and built to conduct the experiments that were designed by using RSM. The use of numerical and graphical optimisation methods have been presented in this thesis and a mathematical model has also been developed. It was reported in this research that the anaerobic digestion process using the beating pre-treatment method produces a higher volume of biogas. It was concluded that the beating treatment achieves 12.65% increase in biogas production from grass silage and the maximum biogas yield is 3410 cc, which can be achieved at the optimal condition: temperature of 37.3 °C and beating time of 2 min 42 s.