In this study, nanocomposites cellulose/CaO-γ-Fe2O3 was successfully synthesized by utilizing egg shell waste as the source of CaO and rice straw as the source of nanocellulose biopolymer and the results were supported by FTIR, XRD and FESEM characterizations. XRD characterization shows that the nano crystal size of CaO-γ-Fe2O3 composite around 58.14 nm was obtained attached on the surface of cellulose and supported by the FESEM surface morphology. Nanocomposites of cellulose/CaO-γ-Fe2O3 was used as catalyst for the synthesis of fatty acid methyl esters from coconut oil through transesterification reaction with methanol. The optimal conditions were obtained 3.6 wt.% catalyst, methanol to oil ratio of 12:1 at 60 °C get the conversion around 89.20 %. Nanocomposites of metal oxide supported by biopolymer have the potential which promising as catalysts in the future and one of them for conversion of coconut oil into fatty acid methyl ester biodiesel.