Triethylene glycol (TEG) is widely used in the gas dehydration process. While absorbing water from the gas, some hydrocarbons may also be absorbed. Knowledge of hydrocarbon solubility in TEG is necessary for TEG regeneration, energy optimization, and economic saving. In this work, experimental measurements and thermodynamic modeling of methane solubility in TEG were conducted. The synthetic method was used to determine the phase behavior of methane + TEG binary system using the Cailletet apparatus. A total of 61 experimental bubble-point data for this system was measured. The mole fraction, temperature, and pressure ranges of the measured data are 0.0142 to 0.0569, 343.16 to 444.95 K, and 2.39 to 12.94 MPa, respectively. It was observed that by increasing the temperature, the solubility of methane in TEG also increases. The thermodynamic modeling was carried out via the phi-phi approach. The Peng-Robinson equation of state (PR EoS), coupled with various mixing rules, was used for this purpose. The classical van der Waals (vdW) mixing rule and more elaborate excess Gibbs energy mixing rules, including the Huron-Vidal (HV), modified Huron-Vidal (MHV1), and Wong-Sandler (WS) mixing rules were considered. It was concluded that the vdW mixing rule with temperature-dependent binary interaction parameters is quite accurate, having an average absolute relative deviation %) of 1.53% for calculated pressures.