Sands are never considered a suitable host material for radioactive waste because of their high permeabilities and low sorption potentials implying fast transport of radionuclides (RN) such as radiocaesium (¹³⁷Cs). Belgium considers poorly indurated clays as one of the options for geological disposal due to their low permeabilities and high sorption potentials. The Neogene sands could become part of the natural barrier in the Belgian radioactive waste disposal concept if a location in poorly indurated Boom or Ypresian Clays is chosen. The sands are characterized by glauconite contents varying from 20-80 wt%. Glauconite is a clay mineral that is aggregated by Fe(III) oxyhydroxides, forming green particles with average grain size of 250 µm. The objective of this study is to determine the ¹³⁷Cs sorption potentials and sorption kinetics of the Neogene glauconite sands. Glauconite ((K,Na)(Fe³⁺Fe²⁺,Al,Mg)₂(Si,Al)₄O₁₀(OH)₂) is described as an iron (Fe) - potassium (K) phyllosilicate, comparable to an Fe-rich illite with K the main interlayer cation. Due to weathering, the mineral can evolve to a smectite-like structure with lower K content and a rim of oxides. Leaching the interlayer cations opens the edges of the layers, creating specific sorption sites for K⁺, caesium (Cs⁺) or ammonium (NH₄⁺). The ¹³⁷Cs sorption on glauconite sands was studied in a batch sorption test. The experiment was set up in a background solution of 100 mM CaCl₂ and 0.5 mM KCl with a solid liquid ratio of 1 g to 30 ml. Initial ¹³⁷Cs activity in the solution was 1.5 kBq ml^-1. The evolution of the activity in solution was measured at different time intervals up to three months after initial spiking. Due to the strong competition with K⁺, ¹³⁷Cs sorption is expressed as the radiocesium interception potential (RIP) or the distribution coefficient at a certain K⁺ concentration (K_D.m_K). A diverse set of glauconite sand samples was selected containing various weathering grades and glauconite contents. To evaluate the effect of the grain size on sorption kinetics, a set of samples was milled to an average 2 µm size. The K_D.m_K values of ranged between 850 and 4900 mmol kg^-1 at 0.5 mM KCl after 14 days of equilibration for glauconite sands, similar to ¹³⁷Cs sorption potentials in the Boom Clay. For glauconite fractions, the sorption potentials range from 3500 to 5500 mmol kg^-1, comparable to illite references (Illite du Puy) with K_D.m_K of 6000 – 7000 mmol kg^-1. The clay sized glauconite has larger sorption potentials that the unmilled grains. However, no significant differences in K_D.m_K were detected between large (>500 µm) and small (125-32 µm) glauconite pellets. The variation in K_D.m_K values among the different Neogene formations are limited, though there is a compositional diversity and a large difference in glauconite content. The ¹³⁷Cs sorption beyond >3 months exceeded that of the 14 days point, this effect was more pronounced for the pellets than for milled grains. Taken together, this study revealed that the ¹³⁷Cs sorption potential of glauconite sands are similar to that of clay deposits when tested in batch sorption.