Trial Design: Open-label, multi-centre, randomised controlled trial comparing hyperthermia plus mitomycin (HM) to mitomycin (MM) in patients with new or recurrence of intermediate-risk non-muscle invasive bladder cancer. Standard adjuvant MM is defined as an immediate post-operative single instillation of MM followed by 6 weekly instillations of MM. The primary outcome measures will be disease-free survival at 24 months. Secondary outcome measures will include recurrence, overall and disease-specific survival in all patients, and recurrence-free survival in patients with papillary disease. The safety and tolerability of HIVEC will be assessed and compared to MM. The effect on Quality of Life will be assessed in all patients.