The thermal treatment of chicken meats was investigated by generalized 2D visible/NIR correlation spectroscopy. Synchronous 2D visible correlation analysis revealed that there are at least two bands around 445 and 560 nm, decreasing in intensity with cooking time. The corresponding asynchronous spectrum indicated that the spectral intensity reduction of the two bands occurs before the intensity variation of the 475, 520, and 585 nm bands. It suggested that the 445 and 560 nm bands be assigned to deoxymyoglobin and oxymyoglobin, respectively, and at least one of the 475, 520, and 585 nm bands assigned to the denatured species (metmyoglobin) of myoglobin. Also, the asynchronous 2D NIR correlation spectrum indicated that C-H fractions are easily oxidized. In addition, strong correlation peaks correlating the bands in the visible, SW-NIR, and NIR spectral regions were observed and discussed.