The experienced trainer returns to the club after leaving three years ago to join Aduana Stars, where he served as assistant to the late Yusif Abubakar and recently Paa Kwesi Fabian.
It is yet to be known the position he would hold at the club, having previously worked as a physical trainer.
Mr Tandoh has been training with the club since last week and he is expected to give guidance to Nii Noi who is acting as an interim coach.
Meanwhile, former assistant coach of the club Ben Adjei would be acting as Team Manager in the absence of Nii Sabahn Quaye, who is reported to be on sick leave.
The Phobians have been without a substantive coach since the departure of Kosta Papic a fortnight ago. Before his resignation, his assistant Asare Bediako had also left.
Days after the departure of the two technical men, goalkeepers trainer Ben Owu also left the club.
Hearts of Oak will face Kotoko in the rescheduled matchday 14 clash at the Accra Sports Stadium on Sunday. Read Full Story