Twist bend nematic (NTB)-forming 9OCCHP5 and 11OCCHP5 dimers were synthesised by one-step condensation of 4-(4-pentylcyclohexyl) benzoic acid and alkyl diol with yields as high as 80%. Although each dimer formed the NTB phase only during the cooling process in a narrow temperature width as large as 4°C, their equiweight mixture formed an NTB phase during both the heating and cooling processes, displaying elliptical polygonal domains and rope-like optical texture. The NTB temperature range became wider by 29–38°C and reduced the orientational order parameter significantly from 0.39 to 0.29 with decreasing temperature.