Solubility of carbon dioxide (CO,) in a low-density polyethylene (LDPE)/titanium dioxide (TiO2) composite was measured using a magnetic suspension balance (MSB) at a temperature from 423 to 473 K and pressures up to 15 MPa. The effect of the TiO2 concentration on the solubility is investigated by varying TiO2 content in the range of 0-20 wt %. Extending the Sanchez-Lacombe equation of state and its mixing rule for binary mixture, a scheme of calculating CO2 solubility in composite from MSB data is developed. The solubility of CO2 in the composites increases in proportion to pressure and exponentially decreases with temperature. The apparent solubility, which is defined by the weight of dissolved CO2 per unit weight of the composite, decreases as the TiO2 content increases. However, the true solubility, which can be defined by the weight of dissolved CO, per unit weight of polymer, is constant, although the TiO2 content is changed.