Sintering of gadolinium doped ceria (GDC) ceramics was done in an alternating current (AC). Electric field ranging from 10 V/cm to 40 V/cm and a current density of 200 mA/mm² were used to investigate densification process. A wide spectrum of frequencies ranging from 0.1 to 1000 Hz were compared to DC field densification. The onset temperature for densification with DC and AC (various frequencies) electric field are correlated to the electro-chemical reduction of ceria. Microstructural analysis of the GDC ceramics sintered under different frequencies indicates towards different internal redox reactions which maybe different for GDC sintered under different frequencies. The grain size trend of ceramics sintered at 20 V/cm is increasing with increasing frequency whereas the reverse trend is true for samples sintered under 40 V/cm. This is speculated in terms of redox reactions at the grain boundary during hte incubation period in the presence of electric field resulting in complete or partial percolation of reduction front.