The objective of this study was to find the optimum amount of montmorillonite (MMT) to be incorporated with microcrystalline cellulose (MCC) to enhance physicochemical properties of oil palm empty fruit bunch (OPEFB)-based regenerated cellulose (RC). In this research, RC was synthesised by mixing 6.5 wt% of OPEFB-MCC with 1-butyl,3-methylimidazolium chloride [BMIM]Cl ionic liquid at 75°C by continuous stirring. RC nanocomposites were prepared by adding 1–5 wt% of montmorillonite (MMT) into RC preparation base. Finished solutions of both types were subjected to solution casting process to obtain thin films. Fourier transformation infrared (FTIR) spectroscopy, tensile test, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), water absorption and contact angle measurements were used as the characterisation tools. FTIR spectroscopy denotes the non-derivative behaviour of [BMIM]Cl ionic liquid. According to SEM images, moderate MMT loading is preferred since high MMT loading shows coarse morphology beyond 3 wt% of MMT. Tensile strength of RC 11 MPa was increased up to 30 MPa as maximum in 4 wt% of MMT loading. Compared with pure RC, TGA curves were shifted to right side with the increased MMT loading and that implies good thermal stability. The highest thermal stability can be seen when the MMT content is 4 wt% since its TGA curve was the rightmost than others. Therefore, MMT can be identified as a good inhibitor for RC to avoid thermal degradation at elevated temperatures. Water absorption was reduced as 91%–37% in 2 h and 96%–41% in 24 h when MMT was increased from 0–5 wt%. Similarly, their contact angle was increased from 30.5o–88.5o for the MMT loading of 0–5 wt%. According to all these results, 3–4 wt% of MMT loading can be proposed as the optimum amount to be added into an RC matrix to utilise these films in packaging, photocatalytic and electrically conductive applications.