Context : The combination of X-ray and near-IR surveys of the central 2 ^ { o } \times 0.8 ^ { o } of the Galactic Centre have revealed a population of X-ray bright massive stars .
However , the nature of the X-ray emission , originating in wind collision zones or via accretion onto compact objects , is uncertain .

Aims : In order to address this we investigated the nature of one of the most luminous X-ray sources - CXOGC J174536.1-285638 .

Methods : This was accomplished by an analysis of the near-IR spectrum with a non-LTE model atmosphere code to determine the physical parameters of the primary .

Results : This was found to be an highly luminous WN9h star , which is remarkably similar to the most massive stars found in the Arches cluster , for which comparison to evolutionary tracks suggest an age of 2-2.5 Myr and an initial mass of \sim 110M _ { \odot } .
The X-ray properties of CXOGC J174536.1-285638 also resemble those of 3 of the 4 X-ray detected WN9h stars within the Arches and in turn other very massive WNLh colliding wind binaries , of which WR25 forms an almost identical ‘ twin ’ .
Simple analytical arguments demonstrate consistency between the X-ray emission and a putative WN9h+mid O V-III binary , causing us to favour such a scenario over an accreting binary .
However , we may not exclude a high mass X-ray binary interpretation , which , if correct , would provide a unique insight into the ( post-SN ) evolution of extremely massive stars .
Irrespective of the nature of the secondary , CXOGC J174536.1-285638 adds to the growing list of known and candidate WNLh binaries .
Of the subset of WNLh stars subject to a radial velocity survey , we find a lower limit to the binary fraction of \sim 45 % ; of interest for studies of massive stellar formation , given that they currently possess the highest dynamically determined masses of any type of star .

Conclusions :