Abstract: A cylinder cart system that incorporates a stabilizing platform for safely loading and offloading of gas/fluid cylinders from trucks and the like is disclosed. The cylinder cart system incorporates a stabilizing platform to which a tank retention mechanism is attached that permits a gas/fluid cylinder to be retrained and raised/lowered via the use of an integrated elevator mechanism that may be manually or power operated. In the raised position, the cylinder cart provides sufficient stability to permit safe offloading of a gas/fluid cylinder onto a pickup truck or the like by a single person. In the lowered position, the cylinder cart incorporates hand truck functionality to permit transport of the gas/fluid cylinder across rugged terrain. An optional integrated safety braking system may in some embodiments provide additional stabilization of the system when the cylinder cart is in the raised position.