Cyclodextrins (CDs) have a polar surface and a hydrophobic cavity that can bind and solubilize long chain fatty acids (FA), while remaining soluble in water. In this study we tested the usefulness of CD for acting as a FA donor to model membranes (egg-PC vesicles). We employed i) fluorescein phosphatidylethanolamine (FPE) to detect changes in membrane surface potential when FA anions adsorb to the outer membrane leaflet ii) entrapped pyranine to measure changes in pH after FA diffusion (flip-flop) across the lipid bilayer and iii) ADIFAB to measure the concentration of unbound FA in water. Upon mixing of oleic acid (OA)/CD complexes with vesicles containing either FPE or pyranine, OA rapidly dissociated from CD, bound to the membrane and underwent flip-flop within 1s (online experiments). In the presence of vesicles, CD maintained the concentration of unbound OA in water low, at almost the same levels measured with albumin. In stopped-flow fluorometry, the mixing of OA/CD with vesicles produced a single exponential decrease in the fluorescence of FPE and pyranine (t1/2 < 50 ms). These kinetics reflect the FA dissociation from CD since FA binding to the membrane and flip-flop are very fast (t1/2 < 10 ms). The delivery of OA by CD was faster than those observed with lipid vesicles (t1/2 = 100 ms) and albumin (t1/2 = 200 ms). Thus, CD is an excellent vehicle to FA and deliver FA to membranes very rapidly while maintaining a low concentration of unbound FA.