Thermodynamic stability boundaries of carbon dioxide + cyclopentane, carbon dioxide + cyclopentanone, and carbon dioxide + fluorocyclopentane mixed hydrates have been investigated in the range of 274.19-293.72 K and up to 4.88 MPa. The phase equilibrium curves of the structure-II mixed hydrates are located at a temperature remarkably higher than that of the structure-I simple carbon dioxide hydrate. The highest temperature point of each four-phase (hydrate, aqueous, cyclopentane derivative-rich, and gas phases) equilibrium curve was 292.60 K (for the first system), 284.78 K (for the second system), and 293.72 K (for the third system) (C) 2013 Elsevier B.V. All rights reserved.