The hospital was shut down in 1995 and last year the HCA secured planning permission for the construction of 280 homes on the 11 hectare site.
The chosen partner will be required to secure reserved matters planning consent and develop a new country park as per a Section 106 agreement, as well as prepare the site before building the new housing. The gross development value is estimated at £187.5m.
A neighbouring site on Selborne Road is also being developed for housing privately and does not form part of this project.
The HCA is working to a start date of September 2017, with completion five years later.
BNP Paribas Real Estate is managing the procurement for the HCA. Prequalification questionnaires need to be returned by 23rd January 2017 and are available by registering at www.lmt-alton.com.