A transfer device (1, 1', 1") for conveying a succession of packaging units along a transfer path, said transfer device (1, 1', 1") comprising: - a first circulating carrier (5, 5") having at least one operative branch parallel to said transfer path; - at least one first conveying element (6, 6') advanced along the first circulating carrier (5, 5''); - a second circulating carrier (7, 7") adjacent to the first circulating carrier (5, 5") and having at least one operative branch parallel to said transfer path and to the operative branch of said first circulating carrier (5, 5"); and - at least one second conveying element (8, 8') controlled independently from the first conveying element (6, 6') and advanced along the second circulating carrier (7, 7"); wherein the first conveying element (6, 6') and the second conveying element (8, 8') are configured to retain therebetween one respective packaging unit of the succession of packaging units and to advance said packaging unit along the transfer path; the operative branches of said first and second circulating carriers (5, 5"; 7, 7") lay on parallel and spaced planes (9, 10) and are aligned with one another in a direction orthogonal to said planes (9, 10) and to said transfer path, wherein the first and the second circulating carriers (5, 5''; 7, 7") are aligned with one another; and wherein the first and the second circulating carriers (5, 5''; 7, 7") are identical to one another; and wherein the first conveying element (6, 6') has a first clamp portion (29a, 29a') and the second conveying element (8, 8') has a second clamp portion (29b, 29b') for gripping and retaining said packaging unit therebetween and wherein the first circulating carrier (5, 5") is superimposed on the second circulating carrier (7, 7"); characterized in that said first clamp portion (29a, 29a') of said first conveying element (6, 6') comprises at least one first indentation (32, 35) configured to partially receive and encircle one side of one respective packaging unit; and wherein said second clamp portion (29b, 29b') of said second conveying element (8, 8') comprises at least one second indentation (33, 36) configured to partially receive and encircle one opposite side of the respective packaging unit, said first and second indentations (32, 33; 35, 36) defining two halves of a substantially closed-loop seat encircling the respective packaging unit, and wherein each of said first and second clamp portion (29a', 29b') comprises at its opposite downstream and upstream ends with reference to said transfer path, one said first indentation and one said second indentation with opposite cavities and adapted to receive two consecutive packaging units advanced along the transfer path itself. - a first circulating carrier (5, 5") having at least one operative branch parallel to said transfer path; - at least one first conveying element (6, 6') advanced along the first circulating carrier (5, 5''); - a second circulating carrier (7, 7") adjacent to the first circulating carrier (5, 5") and having at least one operative branch parallel to said transfer path and to the operative branch of said first circulating carrier (5, 5"); and - at least one second conveying element (8, 8') controlled independently from the first conveying element (6, 6') and advanced along the second circulating carrier (7, 7");