It is well known that the solution characteristics, such as pH and temperature may affect the corrosion mechanism and the corrosion behavior. Lead acid batteries manufacturers have provided modifications into the grid project in order to decrease battery grid weight as well as to reduce the production costs, and to increase the battery life-time cycle and the corrosion-resistance. The performance of lead-acid batteries in automotive applications can significantly be affected by temperature variation. The aim of this study was to evaluate the effects of the microstructural morphology of a Pb-6.6wt%Sb alloy under conditions of hot corrosion. A water-cooled unidirectional solidification system was used to obtain coarse and fine dendritic microstructures. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the corrosion behavior of fine and coarse dendritic samples in a 0.5M H2SO4 solution in three different working temperatures. It was found that independently of the working temperature, samples with finer dendritic microstructures provide better corrosion resistance than coarser ones, which is an indication that the former microstructural pattern may provide a higher battery life-time in severe temperatures than a coarser one.