We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing studies carried out with methanol vapor using impedance spectroscopy demonstrate that the presence of MOF enhances the overall response and lowers the detection limit compared to MOF-free polymer films and bare devices. This can be understood by additional changes of the local polarity of the composite films due to higher adsorption of methanol by the porous MOF particles. We expect that this work will stimulate the design of composite polymeric affinity layers for a range of analytes by a proper choice of dispersed MOF particles.