Nanocellulose was successfully synthetized from microcrystalline cellulose by an acid hydrolysis process. The sample characterization was performed employing X-ray diffraction, zeta potential and confocal Raman microscopy. Nanocellulose-reinforced thermoplastic starch (TPS) composites were prepared by solution casting method, in which a small concentration of nanocellulose improved the elastic modulus of TPS. This property was calculated using the atomic force microscopy nanoindentation method. We conclude that nanocellulose is a good mechanical reinforcement for composites from commercial sources as starch.