The main objective of this study was to determine the mineral composition and the occurrence of the colloidal, and particularly nanosized, mineral phases in the recent marine sediments of different sedimentological environments of the Adriatic Sea. Particularly, detailed investigation of their surface physico-chemical, mineralogical, morphological and geochemical properties were preformed. The influence of organic and inorganic surface coatings on these properties was also investigated. The results obtained showed that the removal of organic matter caused disintegration of aggregates, increase in clay fraction and lowering of mean particle size. Also, an increase in SSA and CEC was observed in all investigated samples. The removal of organic matter had no effect on the charge of mineral particles. The increase in SSA and CEC with particle size diminishing to colloidal dimension was ascribed to the accumulation of clay minerals and Fe and Mn oxides and oxyhydroxides in finer sediment fractions, while the intensity of this increment was the result of different distribution of these mineral phases. Iron and manganese oxides and oxyhydroxides on the surfaces of mineral particles additiona lly increased their SSA. The results showed an increase in concentrations of metals associated with aluminosilicates and Fe and Mn oxides and oxyhydroxides with particle size lowering. The removal of Fe and Mn oxides and oxyhydroxides significantly affected the distribution of Co, Cu and Mo on account of their association with Mn oxides and oxyhydroxides and indicated the importance of Fe oxides and oxyhydroxides in cycling of As in the environment. The significant occurrence of carbonates in colloidal mineral phase was determined in the sedimentary environment where their presence was the result of authigenic formation. In sediments where carbonates were a product of mechanical and chemical weathering, their occurrence in colloidal mineral phase was very limited.