The electrocapillary effect is the change in interfacial tension between two immiscible liquids when subjected to an electric field across the interface. The change in interfacial tension occurs due to variations in the surface charge density of adsorbed ions or polar species at the interface. In the present work, we provide fluid mechanical insights into electrocapillarity-based dynamics of an interface between a passive air layer and a thin liquid film that has small, but finite electrical conductivity. We formulate and solve mathematical equations that model the situation in which a liquid film bounded by an air layer of controllable thickness is sandwiched between two electrode plates, and an electric field is applied across the layers. As the liquid and air have different conductivities, free charges would accumulate at the liquid-air interface to ensure that current is conserved across the layers. In our model, the interfacial tension is assumed to vary as per the classical Lippmann's equation. The present mathematical model describes spatiotemporal variation of the film height and interfacial charge density as a function of the applied potential, air layer width, and the sensitivity of interfacial tension to the electric potential. Our results show that ultrathin liquid films (<100 nm) in presence of electrocapillary Marangoni effect are destabilized and break up faster than in its absence. Furthermore, by controlling the air gap width, different morphological patterns can be generated. Finally, we illustrate that the dynamics is profoundly affected if the electrode plate bounding the liquid film possesses patterned wettability. © 2021 Elsevier Ltd. All rights reserved.