A layer of TiD2 (5 × 1019 TiD2 cm−2) was prepared by deuterium implantation into a polycrystalline titanium foil at room temperature. The foil was subsequently installed in front of a large area surface barrier detector in a vacuum of 10−7 mbar to measure the reaction products of the two possible D-D fusion reactions. After a counting period of 30 hours, at most two fusion products were found, which limits the reaction probability to below 8 × 10−24 fusion processes per second and per deuterium pair in the implanted layer.