Thermal deformations and phase transformations of evennumbered paraffins C_nH_2n+2(n=20, 22, and 24) have been investigated in a thermal X-ray diffraction study. In homologs with n=20 and 24, phase transformations occur in two steps: triclinic-to-orthorhombic and orthorhombic-to-hexagonal transitions. An orthorhombic rotator phase of even n-paraffins is described for the first time. A crystal-chemical model of the phase transformations of the homologs is suggested.