We report simultaneous cooling and trapping of metastable 84 Kr ( 84 Kr*) and metastable 86 Kr ( 86 Kr*) atoms by overlapping the cooling laser beams for these different isotopes in the same region of a magneto-optical trap (MOT). Approximately 2 × 10 5 atoms of each isotope were trapped in this two isotope-MOT (TIMOT). We have investigated the heteronuclear collision trap loss rates for each isotope due to the presence of cold atoms of other isotope using the TIMOT loading curves. The two body heteronuclear loss rate coefficient * * Kr Kr 84 86 β − (i.e. for the loss of 84 Kr* due to presence of 86 Kr*) and the reciprocal loss rate coefficient * * Kr Kr 86 84β − (i.e. for the loss of 86 Kr* due to presence of 84 Kr*) are measured to be (8.7 ± 0.8) × 10 −10 cm 3 s −1 and (8.8 ± 0.8) × 10 −10 cm 3 s −1 respectively for laser beam intensity values of 21 mW cm −2 (for cooling of 84 Kr*) and 64 mW cm −2 (for cooling of 86 Kr*). The dependence of heteronuclear cold collision loss rate on cooling laser beams intensity has also been studied and compared with homonuclear cold collision loss rate.