Electrical double layer capacitors (EDLCs) are energy storage devices which primarily utilize ionic adsorption and high surface area electrodes to store electrostatic charge at electrode/electrolyte interface. In order to describe and correlate electrode architecture to the energy and power performance of capacitors, first principle models that can explain both the ac and dc response of the capacitor need to be developed. In this work, we describe an ab initio mathematical model that take into account both the double layer and interfacial resistance contributions at the electrode/electrolyte interface. The model was tested, and validated using experimental data of various carbon-based EDLCs using both electrochemical impedance spectroscopy (EIS) and galvanostatic discharge data. Physical parameters of the model were obtained through non-linear regression of frequency-domain EIS data, which was then transformed into time domain using numerical inverse Laplace transform to predict the potential-time discharge response of the capacitor. The experimental data was in excellent agreement with the model predictions.