Pervaporation (PV) performance of Poly (vinyl alcohol) (PVA) membranes were studied for isopropanol dehydration and the effects of the feed temperature and concentration were investigated. First, the effects of incorporation of two different fillers (carbon nanotubes (CNTs) and titanate nanotubes (TNTs)) into PVA matrix were examined. Next, supported membranes were prepared to study the effect of the membrane thickness and the hydrophilicity of the support layer: in other words, separation performance of water from isopropanol were investigated for mixed matrix membranes (MMMs) supported by polyethersulfone (PES) and sulfonated polyethersulfone (SPES). Owing to strong Van der Waals interactions among CNTs walls and their strong hydrophobicity, modification of the CNTs were performed through covalent and non-covalent modifications. Moreover, the effect of the amount of modifications and the type of polymer used for modification of CNTs were studied. PV experiments indicated that MMMs with covalently-modified-CNTs exhibited different separation abilities from MMMs with non-covalently-modified-CNTs. The obtained results showed that the flux decreased and the separation factor increased when higher amount of polymer were wrapped around CNTs. Furthermore, the observations indicated that the type of the polymer wrapped around CNTs played an important role on suppressing Van der Waals attractions among nanotubes as well as the chemical interactions between the polymeric matrix and the CNTs. As for MMMs containing TNTs, the PV results revealed that the maximum amount of flux and PSI index were higher than those obtained for MMMs with modified CNTs. However, the maximum value for separation factor was observed when 3 wt% Of the CNTs wrapped with 5wt% of poly(styrenesulfonate) were incorporated into PVA. For membrane supported by PES, as is expected, the flux of the membranes increased by decreasing the thickness of the membranes while there was a common trade-off between the flux and the separation factor. However, an anti-trade-off behavior was observed between the flux and the separation factor when SPES was used as the support layer. As a matter of fact, the compatibility between the support layer and the selective top layer increased when polyethersulfone was sulfonated. Strong interactions between sulfonic groups of SPES and OH groups of PVA and increased compatibility between the hydrophilicity of the support and the selective layers were resulted in formation of defect-free and ideal interface in PVA-Based-membranes supported by SPES. So, the mass traort resistance decreased for MMMs supported by SPES. In summary, the maximum amount of PSI index was about 795 corresponding to SPES-supported-MMMs containing 4 wt% of TNTs. The best separation factor was 3123 when 3 wt% of non-covalently-modified-CNTs were dispersed into PVA. Finally, the maximum flux of 0.58 kg/m 2 h was obtained for the supported membrane by SPES with selective top layer containing 10 wt% of TNTs. Key words: Pervaporation, Flux, Separation Factor, Nanotubes, Mixed Matrix Membranes, Thickness.