Holding structure for cylinder trailers, comprising at least one load-bearing frame that can be attached to a cylinder trailer intended to transport a plurality of storage tanks of a fluid along at least one direction of travel, each of said storage tanks comprising: - at least one main body (E, G1, G2) of elongated conformation extending along a corresponding longitudinal axis and comprising: - a central portion substantially cylindrical in shape having a diameter; and - a pair of ogival portions (G1, G2) associated with the ends of said central portion, wherein a first ogival portion is positioned behind said cylinder trailer with respect to said direction of travel and a second ogival portion is positioned in front of said cylinder trailer with respect to said direction of travel; - at least one pair of fittings (R1, R2) for taking and/or loading said fluid, arranged at the ends of said main body (E, G1, G2), wherein a first fitting is associated with said first ogival portion and a second fitting is associated with said second ogival portion; - at least one holding element associated with said load-bearing frame, adapted to hold at least one corresponding storage tank and defining at least one work surface adapted to abut against at least one corresponding second ogival portion and to prevent the storage tank itself from shifting along at least one direction of sliding substantially parallel to said direction of travel; characterized by the fact that said holding element is of the slab-shaped type and lies on a plane of development which is inclined with respect to said direction of sliding, said work surface being substantially flat. - at least one main body (E, G1, G2) of elongated conformation extending along a corresponding longitudinal axis and comprising: - a central portion substantially cylindrical in shape having a diameter; and - a pair of ogival portions (G1, G2) associated with the ends of said central portion, wherein a first ogival portion is positioned behind said cylinder trailer with respect to said direction of travel and a second ogival portion is positioned in front of said cylinder trailer with respect to said direction of travel; - a central portion substantially cylindrical in shape having a diameter; and - a pair of ogival portions (G1, G2) associated with the ends of said central portion, wherein a first ogival portion is positioned behind said cylinder trailer with respect to said direction of travel and a second ogival portion is positioned in front of said cylinder trailer with respect to said direction of travel; - at least one pair of fittings (R1, R2) for taking and/or loading said fluid, arranged at the ends of said main body (E, G1, G2), wherein a first fitting is associated with said first ogival portion and a second fitting is associated with said second ogival portion; - at least one holding element associated with said load-bearing frame, adapted to hold at least one corresponding storage tank and defining at least one work surface adapted to abut against at least one corresponding second ogival portion and to prevent the storage tank itself from shifting along at least one direction of sliding substantially parallel to said direction of travel;