Vitamin C (L-ascorbic acid) is an essential micronutrient that serves as an antioxidant and as a cofactor in many enzymatic reactions. Intestinal and renal absorption of the vitamin is mediated by the apical L-ascorbic acid cotransporter SVCT1 (SLC23A1). We explored the mechanisms of SVCT1-mediated L-ascorbic acid transport using radiotracer and voltage-clamp techniques in RNA-injected Xenopus oocytes. L-Ascorbic acid transport was saturable (K_0.5 70 µM), temperature dependent (Q₁₀ 5), and energized by the Na⁺ electrochemical potential gradient. We obtained a Na⁺/L-ascorbic acid coupling ratio of 2:1 from simultaneous measurement of currents and fluxes. L-Ascorbic acid and Na⁺ saturation kinetics as a function of cosubstrate concentrations revealed a simultaneous transport mechanism in which binding is ordered Na⁺, L-ascorbic acid, Na⁺. In the absence of L-ascorbic acid, SVCT1 mediated presteady-state currents that decayed with time constants 3-15 ms. Transients were described by single Boltzmann distributions. At 100 mM Na⁺, maximal charge translocation (Q_max) was 25 nC, around a midpoint (V_0.5) at −9 mV, and with apparent valence (z) −1. Q_max was conserved upon progressive removal of Na⁺ whereas V_0.5 shifted to more hyperpolarized potentials. Model simulation predicted that the presteady-state current predominantly results from an ion-well effect on binding of the first Na⁺ part-way within the membrane electric field. We present a transport model for SVCT1 that will provide a framework for investigating the impact of specific mutations and polymorphisms in SLC23A1, and help us better understand the contribution of SVCT1 to vitamin C metabolism in health and disease.