A method and apparatus for determining pore size distribution and/or the presence of at least one killer pore in at least a portion of a porous film deposited upon a substrate are disclosed herein. In one embodiment, there is provided a method for determining pore size distribution comprising: providing the substrate having the film deposited thereupon wherein the film comprises pores and wherein the pores have a first volume; exposing the film to an adsorbate at a temperature and a pressure sufficient to provide condensation of the adsorbate in pores and wherein the pores after the exposing step have a second volume; and measuring the difference between the first and the second volume using a volumetric technique; and calculating the pore size and pore volume using the change in the first and the second volume, the pressure, and a model that relates pressure to pore diameter.