Both smectic hexatic phases, Hex-B and Sm-F, were found in some three-ring 2-methylthienyl derivatives terminated with alkoxyl substituents. In a homologous series THI the molecular terminal chains promote either tilted (for abort chains) or orthogonal (for long chains) hexatic mesophases. For intermediate length chains (having 24 or 25 carbon atoms), the phase sequence is Hex-B - Sm-F - SmC - Sm-A. This phase sequence allows observation of two new triple points involving Hex-a phase. For some halogen substituted thienyl derivatives other mixed-lilt type phase sequence, Cry-G - Sm-F - Hex-B - Sm-rt is found phase transitions involving hexatic phases were studied by DSC and X-ray scattering method.