The kinetics of dissociative adsorption of HCOOH on Pt(100), Pt(610), Pt(210) and Pt(110) single-crystal electrodes has been investigated. The oxidation of dissociative adsorbate (DA) derived from the dissociative adsorption of HCOOH was used as a probe reaction together with the potential-step technique of short time windows. The quantity Q(ad) of DA produced at a given potential E(ad) and in a defined time window t(ad) of adsorption has been determined systematically. At fixed t(ad) peaked curves of Q(ad) versus E(ad) in the potential range between -0.25 and 0.25 V/SCE have been obtained on all four electrodes. The maximum rate of dissociative adsorption of HCOOH decreases in the order Pt(110) > Pt(210) > Pt(610) > Pt(100).