Sites under consideration include: Soho and central London; Balham and Battersea, south-west London; Ealing, west London; and the City, Dalston, Shoreditch and Hackney to the east.
Grand Union is also considering expanding nationwide to sites in Brighton, Cambridge, Bath, Cardiff, Oxford, Canterbury, Birmingham, Edinburgh, Glasgow, Manchester, Guildford (Surrey) and Leeds.
Grand Union said it will focus on high-footfall, high-density, commercial locations, of between 4,000sq ft and 10,000sq ft.
Chief executive Adam Marshall said: “Despite challenging trading, we have grown steadily since the launch of our first site in Camden in 2006. We look forward to building on our success and accelerating growth of the company.”