"These results confirm management's assessment of the prospectivity of Thor's Douta Project and builds on our 2017 exploration success," said Segun Lawson, the company's president and chief executive.
"Notably, the results are comparable with other major deposits in the region, which raises the potential of a discovery emerging at a significant scale.
"Thor is looking forward to announcing the remaining results from the current programme in July and assessing mineral resource potential."
Thor said it had encountered near-surface gold mineralisation, along with continuous mineralisation down dip and over a 3km strike.
It is open on strike and at depth.
Highlight assays include 9 meters (m) at 1.84 g/t (grams per ton) gold and 3m at 13.2 g/t gold - both from one hole.
The same hole also yielded an intersection of 10 metres at 1.86 g/t (gram per ton) of the yellow metal.
Douta lies in the prospective, gold-endowed Birimian Greenstone belt in south-east Senegal, West Africa and is within 5km of Randgold's 3.6 Moz (million ounce) Massawa resource.
The Makosa discovery is the first of several significant exploration targets to be drilled by Thor within the project.
So far, 13 holes for 1,531m and 24 RC drillholes for 2,000m have been completed over the Makosa prospect and 7,800m of the planned 8,000m have been completed in the 2018 RC (reverse circulation) program over a strike length of around 2.2km.
Shares were unchanged at C$0.195.