This study investigates the effect of pulse cathodic protection as compared to conventional cathodic protection on corrosion and electrochemical conditions under the disbonded coating of X52 pipeline steel. In this regard, a laboratory test setup that could simulate the underlying conditions by applying cathodic protection was designed and made. Coupons with dimensions of 20×10×5 mm, made from X52 pipeline steel were placed under the simulated coating disbondment, while the length and the gap size of disbondment were 200 mm and 3 mm respectively. By placing the cell in a simulated soil solution C2, conventional pulse CP of -870mV SCE was applied to the open mouth (OM) of simulated coating disbondment. For pulse cathodic protection, frequencies of 1000, 5000, and 10000 Hz were applied. Result showed that for conventional CP, potential failed sharply to Open Circuit Potential (OCP) values at 7 cm from the OM of the simulated coating disbondment. For pulse catholic protection, at frequency of 10000Hz, in contrast to conventional CP, no drop in CP potential was observed. In fact, the potential gradient which usually is observed under simulated coating disbondment when conventional CP being applied was not observed. The removal of the potential gradient at this frequency is due to concentration polarization decreasing inside the crevice, which significantly depends on the pulsed waveform parameters. Also, investigating the chemical and electrochemical conditions under coating disbondment showed that there was more uniform distribution of pH and potential with increase in frequency of pulse cathodic protection, as compared to the conventional CP. Keywords: Corrosion, Disbonded Coating, Pulse Cathodic Protection, Pipeline Steel.