Several concepts can be applied for gas detection using solid ionic conductors. The fundamental characteristics and the essential variables for proper design of electrochemical cells are analyzed in terms of the sensing principle applied. The principal properties for materials as components of electrochemical devices are being illustrated. Employment of dynamic method allows implementation of the Fourier coefficients to generate a complex plane plot representation. This can be particularly useful for extracting information regarding the selectivity of an electrochemical cell to multiple gas species. Moreover, modeling the system response upon a periodical perturbation can be beneficial on understanding the individual processes and optimizing the overall performance.