Time reversal symmetry (TRS) and inversion symmetry are principal symmetries assumed to provide the necessary conditions for superconductivity (SC) with spin singlet pairing (for the former) and spin triplet pairing (for the latter). Although inversion symmetry is missing in the crystal structure of CePt3Si, spin triplet pairs are observed in the SC condensate, additionally mixed with spin singlet pairs. Unexpectedly, the non-centrosymmetric SC LaNiC2 shows evidence of TRS breaking. In order to proof whether or not TRS breaking is an inherent property associated with the missing inversion symmetry, we plan to carry out systematic investigations on this subject, starting with superconducting BaPtSi3. A most direct way of detecting TRS breaking is muon spin relaxation. Therefore, we request 4 days on the MuSR spectrometer of ISIS, investigating whether or not TRS is broken in BaPtSi3.