Data for the diffusivity and solubility of methanol in blends of polyethersulfone (PES) and a liquid crystalline copolyester (poly(hydroxy-benzoic acid (73 mol%)-co-hydroxy-naphthoic acid (27 mol%)) (LCP) are reported. Samples taken from injection molded and compression molded specimens over a wide composition range were studied by gravimetry (sorption and desorption), dielectric spectroscopy, differential scanning calorimetry and scanning electron microscopy. The sorption of methanol in PES led to the formation of an ordered phase. The sorption curves were S-shaped and they could be described by a diffusion model assuming a concentration-dependent diffusivity and time-dependent boundary conditions. The solubility of methanol in the blends was strictly proportional to the PES content. The zero-concentration-diffusivity decreased strongly with increasing LCP content and it was dependent on the morphology. Injection molding yielded samples with a fibrillar LCP phase with a greater continuity of the PES component and a high diffusivity tin relative terms). Compression molding led to samples with a more continuous LCP component even at low LCP contents and a low diffusivity.