A method, and product thereof, for modifying the surface of recycled sulfur-cured rubber via surface devulcanization that minimizes alteration of the network structure of the recycled sulfur-cured rubber, while generating strong tack between mixed recycled rubber and fresh rubber for optimal adhesion upon subsequent co-curing. In one embodiment, the surface of recycled rubber is devulcanized by treating recycled rubber with a thiol and a base dissolved in a solvent that does not effectively penetrate and only minimally swells vulcanized rubbers.