A dozen unpaid staff were recruited at the Oxford University Hospitals Trust (OUH) last year to offer prayer and participate in memorial services but a shortage remains.
In a statement, the Diocese of Oxford said: "It's not just big city hospitals that require support.
"In the case of the Oxford Health NHS Trust, the greatest need is in the community hospitals in Abingdon, Witney, Bicester, Wallingford, Oxford City and Didcot."
At Wexham Park Hospital in Berkshire, where 38 Anglican and 26 Roman Catholic chaplaincy volunteers patrol wards in lilac polo shirts, the demand for spiritual support has risen by 40 per cent since 2012.
A chaplain at the site in Slough, Revd Jennifer Sistig said: "Just the simple of act of conversation is something that is very important to some people in hospital."
Rev Sistig also reported that there are regularly 100 requests from patients for support on the chaplaincy board at any one time.
Applications for new chaplaincy volunteers at OUH open next month. A training programme gets underway after Christmas.