Abstract: A hyperbranched dendritic polyether, which optionally is further processed, such as further chain extended, chain terminated and/or functionalised. The hyperbranched dendritic polyether is obtained in a process comprising the step of thermally initiated cationic ring-opening polymerisation of at least one oxetane having at least two reactive groups of which at least one is an oxetane group. The thermally initiated ring-opening polymerisation is performed using an effective amount of at least one initiator, such as a thermal onium salt, a Lewis acid and/or a Brønsted acid. The terminal groups in said hyperbranched dendritic polyether are substantially hydroxyl groups and used for said optional further processing.