The academies will open in existing buildings before new ones are built
Two schools in West Sussex will close and be replaced with academies, county councillors have agreed.
Developing the academies in Lancing and Littlehampton will see investment of more than £54m in building projects, councillor Pat Arculus said.
Boundstone Community College and Littlehampton Community School will close in August 2009, she added.
The academies will open on existing school sites the following month, with new buildings expected to open in 2011.
Feasibility work is still under way but government approval is expected in the near future, Mrs Arculus said.
She said: "The academies will not only provide a first-class education for many generations to come, but will also make a significant contribution to their local communities too."
The Littlehampton Academy will have £30m invested in new buildings, and £24.6m will be put into the Boundstone Academy site, she added.
Mrs Arculus said the approval of the plans was "a major milestone".