Recently the compound TlNi2Se2 has gained interest as a potential playground of unconventional superconductor effects. Heat capacity and magnetization measurements hint at the possibility of d-wave pairing symmetry for the Cooper pairs, which would be an important discovery, providing a bridge between the heavy-fermion superconductors and the extremely technologically relevant high-Tc cuprate materials. The system also appears to be multiband with two superconducting gaps. Muon spin rotation measurements are vital in order to confirm these initial observations, and make accurate measurements of the penetration depth, gap symmetry and magnitude, and determine if time reversal symmetry is preserved.