In this paper, phase equilibrium and viscosity data were experimentally obtained for a CO2 + n-dodecane (n-C12H26) binary mixture. The experiments, which were conducted with a custom-made PVT cell of variable volume connected to an oscillating-piston viscometer, considered CO2-based mixtures with mole fractions between 0.2 and 0.8, and temperatures spanning from 283 to 353 K. The experimental tests were complemented with theoretical analysis, which relied on the Peng–Robinson, PC-SAFT, and PCP-SAFT equations of state (EoS) to correlate the bubble point pressure, while the friction theory (f-theory) coupled to either the Peng–Robinson or the PC-SAFT EoS was used to correlate the measured viscosity. The analysis revealed that the smallest absolute deviations for the bubble point pressure and viscosity, respectively, are 2.2 and 8.51%, and were obtained with PCP-SAFT EoS and f-theory/PC-SAFT.