Context : Wolf Rayet/black hole binaries are believed to exist as a later evolutionary product of high-mass X-ray binaries .
Hundreds of such binaries may exist in galaxies , but only a few of them are close enough to be observed as X-ray binaries .
Only a couple of candidates have been reported so far .

Aims : Based on XMM-Newton observations , we report the positional coincidence of the brightest X-ray source in NGC 300 ( NGC 300 X-1 ) with a Wolf-Rayet candidate .
Temporal and spectral analysis of the X-ray source is performed .

Methods : We determine an accurate X-ray position of the object , and derive light curves , spectra and flux in four XMM-Newton observations .

Results : The positions of the X-ray source and the helium star candidate coincide within 0 \aas@@fstack { \prime \prime } 11 \pm 0 \aas@@fstack { \prime \prime } 45 .
The X-ray light curves show irregular variability .
During one XMM-Newton observation , the flux increased by about a factor of ten in 10 hours .
The spectrum can be modelled by a power-law with \Gamma \sim 2.45 with additional relatively weak line emission , notably around 0.95 keV .
The mean observed ( absorbed ) luminosity in the 0.2–10 keV band is \sim 2 \times 10 ^ { 38 } \text { erg } \text { s } ^ { -1 } .

Conclusions : NGC 300 X-1 is a good candidate for a Wolf-Rayet/black-hole X-ray binary : its position coincides with a Wolf-Rayet candidate and the unabsorbed X-ray luminosity reached L _ { 0.2 - 10 \text { keV } } \sim 1 \times 10 ^ { 39 } \text { erg } \text { s } ^ { -1 } , suggesting the presence of a black hole .