The benefit of using alkali-treated hemp fibre as the reinforcement for rotationally moulded evaluated in this research. Untreated and alkali treated hemp fibre were characterised using different techniques such as scanning electron microscopy (SEM), thermal analysis, and Fourier transform infrared spectroscopy (FT-IR). These techniques showed that the alkali treatment removed non-cellulosic components from hemp fibres, which improved their separation and thermal resistance. Composites with alkali treated fibre resisted the exposure to elevated temperatures for prolonged periods (characteristic of the rotational moulding process) with no apparent signs of thermal degradation, unlike when untreated fibre was used. The effect of using maleic anhydride grafted polyethylene (MAPE) as a coupling agent was also investigated. The addition of 3 wt% MAPE improved the properties tensile strength and Young’s modulus of composites with treated hemp fibre, which was attributed to better fibre-matrix adhesion. Different fibre contents were assessed in this research to produce rotationally moulded composites; a poor fibre distribution was observed above 5 wt% fibre content, which resulted in low tensile strength and Young’s modulus.