A collapsible securing system for securing medical oxygen cylinders for passenger seats including: (i) a base configured such as to be positioned on the passenger seat; (ii) an intermediate securing structure for oxygen cylinders connected to the base by three legs; (iii) a gripping structure, connected to the intermediate securing structure by at least one pivot in common with the intermediate securing structure, and (iv) a fitting system comprising the seatbelt and two straps secured from one end the gripping structure and from the other end thereof to the fitting of the seatbelt to the passenger seat.