This study investigated the effects of different isotherm temperatures on the thermal behavior and physical properties (i.e., degree of cure, density, fiber volume fraction, and void content) of quasi-isotropic carbon fiber reinforced polymer composite laminates. First, the curing kinetics of a new commercial prepreg, Hexply®8552S, was investigated by isothermal differential scanning calorimetry (DSC). The nth-order, autocatalytic, and Kamal & Sourour models were used to determine curing kinetic parameters that fit the experimental data. The results showed that the phenomenological model of Kamal & Sourour was the most appropriate, as indicated by the relatively high values of the adjusted R square. Based on the kinetics results, autoclave processing was used to produce laminated composites. The isothermal curing temperatures were 160, 180, 190, and 205 °C, respectively. The results showed that the isotherm temperature significantly influenced the final degree of cure, density, and void content. At 180 °C, the highest values of degree of cure and density were obtained, while the lowest values of void content were remarqued.