Mid-infrared spectroscopic characterization of doped layers is a rapid, contactless and non-destructive method of determining doped semiconductor layer properties, being used as an inline monitoring tool in industrial environments. Extending this technique to transparent conductive oxides (TCOs) would be tremendously beneficial, which otherwise requires intensive characterization to determine the layer properties. This work analyzes the usefulness of IR reflectometry in characterizing three different types of TCOs deposited on glass. An optical model is developed which fits to the experimental reflectance data and estimates critical parameters like effective mass ratio, plasma frequency and the complex refractive index of the layers in the mid-IR range.