Tore is expected to put pen-to-paper on a one year loan deal with an option for West Ham to buy him out later today.
Besiktas initially wanted an upfront transfer fee for Tore but compromised with the East London based club on a loan fee and the option for West Ham to sign him at a later date.
The Black Eagles were determined to get a fee as they are currently under FFP investigation and must show higher revenues than spending over the next season.
The Turkish intentional will become the first player from Besiktas to join Slaven Bilic at the Hammers since he left the Black Eagles last summer.
Tore excelled at Besiktas under the stewardship of Bilic and has actually played longer under his command – two seasons – than any other current West Ham player.