Adsorption ability, stability and corrosion inhibition of phoenix dactylifera (date palm) seed extract (PDSE) as a natural corrosion inhibitor were studied on mild steel (MS) in 1 M HCl solution after different exposure times. Linear polarization resistance (LPR), potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) techniques were utilized to define the inhibiting performance of the extract on the rate of corrosion. The stability of the organic film formed over the metal surface was investigated with the help of chronoamperometry (CA) technique. The MS surface was characterized using scanning electron microscopy (SEM), x-ray diffraction (XRD) and contact angle measurements. Surface charge of the metal after exposing to the solution was determined by measuring the potential of zero charge (PZC) using the EIS technique and an adsorption mechanism was proposed. The results of the electrochemical measurements showed that PDSE reduces sufficiently the rate of MS corrosion. The SEM studies showed that the inhibitor strictly attached to the metal surface and form a protective film over the metal surface. The average inhibition efficiency determined from LPR, EIS and PP techniques was found to be 97.3%, which is quite efficient for the practical applications.