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In the state of Rio Grande do Norte exists outcrops of cliffs that belongs to the Barreiras Formation, which cities and infrastructure works are developed on. In this region, mass movements are reported in relevant proportions, especially in rainy season. The aims of this work were to study the geotechnical properties of the Barreiras Formation soils that make up the Barra de Tabatinga / RN beach cliff and to evaluate the stability of the cliff from the deterministic point of view. The studied cliff was divided into three predominant soils, which are located at the base (AM-01), middle (AM-02) and top (AM-03) layers. In these soils, were performed characterization tests (geotechnical, chemical, and mineralogical), tests to determine the soil-water retention curve, permeability tests, triaxial and diametral compression tests under saturated and unsaturated conditions. Samples AM-01 and AM-02 showed bimodal soil-water retention curves, unlike the top sample, which presented unimodal fit. In addition, all of them presented close to zero cohesion and angle of friction around 30° in the saturated condition. However, when unsaturated, the strength parameters increased considerably, especially the cohesion. the tensile strength decreased with the increase in the degree of saturation reaching negligible values in all soils when saturated. The upper soil is the most permeable of the studied soils, presenting a permeability coefficient compatible with pure sand. [ABSTRACT FROM AUTHOR]