A novel differential photoacoustic cell (DPC) for the study of dynamical processes has been developed. The DPC has the capability to measure in real time the amplitude and phase signals for the reference and the sample under study. The simultaneous measurement of both signals eliminates the instrumental function, and the presence of noise, due to any deviation originated by electrical, optical, and environmental factors. The DPC can be used at different temperature profiles in order to obtain the instrumental function IF(t,T). The DPC also has all the elements of an electrochemical cell capable of following the electrochemical processes. As a result of this new instrumentation it is possible to obtain in real time the amplitude and phase signals coming from the sample without any interference from the system and the viability to monitor in situ electrochemical and thermal processes. Two cases are presented as an illustrative demonstration of work fields: the electrodeposition of zinc on a steel substrate as well as the study of water and calcium ion diffusion into organic layers.