Surface energies and dynamic vapour sorption (DVS) plays an imparative role in drug polymer interaction in the formulation development for a number of applications. Powdered films of two pH sensitive polymers namely hypromellose phthalate (HPMCP) and methacrylic acid copolymer NF (Eudragit L30-55) were studied for surface energy analysis employing inverse-phase gas chromatography (IGC) which is a well-known physi- cal technique in acquiring significant information about surfaces of pharmaceutical powder or film. The mean surface energies of Eudragit L30D-55 and HPMCP films were found to be 40.48 mJ/m2 and 55.03 mJ/m2 respectively and significantly different from each other. Due to this difference, tablets were coated separately with HPMC and Eudragit L30D-55 in equal amount and were subjected to Near-Infra Red FTIR (NIR) equipped with DVS analyser for measuring DVS changes versus relative humidity (RH) in both coated tablets. Initial NIR and changing RH (25–75% up to 90%) of coated tablets were recorded after 15 minutes throughout the experiment. Eudragit L30-55 coated tablets showed no changes in NIR up to 90% of RH. However, HPMCP showed significant changes in NIR at 90% RH, indicating interaction of moisture with drug due to greater surface energy of HPMCP compared to Eudragit. These results confirmed good correlation between surface energy and relative humidity of two polymeric films and coated tablets. The study also shows quantification of drug and polymer by in vitro release of phthalyl group.