Enhancements to a hospital in Banbury are the result of more than half a million pounds raised by supporters.
The expanded space was built at Horton General Hospital's Brodey Centre where cancer patients are treated.
The department's four treatment spaces have been doubled in a rebuild that took six months.
Mike Fleming, director of the hospital, said: "We are so grateful for the support from many different individuals and groups in our local community."
The new building was designed to provide more privacy for patients and their relatives.
It includes a larger waiting area and extra space, including a new mezzanine level.
Thanking the fundraisers, Mr Fleming said: "It is no exaggeration to say that without them we would not have our beautiful new centre which will be of so much benefit to local people."
Anita Joice, a senior staff nurse at the centre said: "It is also great news that fewer patients will now have to travel for their treatment and that more can be treated nearer to home, here in Banbury."
The Brodey Centre originally opened in 1998.
It treats approximately 2,000 patients a year who would otherwise have had to travel to Oxford.