Synthesis of methylcellulose (MC) using dimethyl carbonate (DMC) with conventional and green methods has been conducted. The cellulose used in this synthesis was obtained from sago waste, which contains 86.67% cellulose. All the methylation products were analyzed using IR and 1H-NMR spectrometers. The determination of cellulose content was done using TAPPI T-203 method, while the degree of substitution (DS) was based on the Zeisel Method. Conventional synthesis of MC was performed using Na2HPO4 (12:1), DMC and NaCl 5% (w/v) (volume ratio = 10:10) at 90 °C. The reaction time was varied (2 to 5 hours); the optimum condition was reached in 3 hours and gave the DS of 1.028. Green synthesis of MC was conducted by employing microwave and sonochemistry techniques. Synthesis MC with the microwave was carried out at the power of 400 W for 200 seconds and gave the DS of 1.036. Synthesis MC with sonochemistry (the variation time 1 to 3 hours) was conducted at the optimum time of 2 hours and gave the DS of 0.646. The DMC volume was also varied (17.5; 20; 22.5; 25; and 30 mL), where the volume ratio of 1:24 gave the highest DS of 1.177. The microwave technique is the best method for synthesis MC compared to conventional and sonochemistry techniques.