Higher group sales helped to fuel the rise as well as a focus on own-brand ranges – which have bigger margins than designer labels – in the 26 weeks to 27 February.
The group's net debt fell to £511.5m down from £927.2m a year ago.
The UK’s second-largest department store behind Marks & Spencer said it expected the trading environment to be "broadly neutral" in the second half.
First-half sales from stores open a year rose 0.3 per cent ahead of forecasts of for flat sales.
Chief Executive Rob Templeman said: “Throughout the last 18 months of recession, Debenhams has consistently achieved growth in sales, margins and trading profits. We made further progress in delivering our strategy in the first half and are pleased with our performance.”