A nano-sized MoO2/C composite was synthesized using a spray pyrolysis technique, and investigated as an anode material for Li-ion batteries. Spherical MoO2/C particles with the monoclinic phase were obtained without any impurities, and with a primary particle size in the range 30–50 nm. Structural variation of the prepared MoO2/C during Li+ insertion was examined by in situ X-ray diffraction and selected area electron diffraction analyses. The structural analysis results indicated that no conversion reaction was activated in the MoO2/C composite. The electrochemical tests demonstrated that the rate-capability and capacity retention of the synthesized materials were improved significantly, which could be attributed to the effective carbon distribution and nano-sized primary particle resulting from the low-synthesis temperature. Therefore, control of the powder morphology and minimization of the primary particle size are found to be essential for achieving the enhanced electrochemical properties in MoO2 anode materials.