Decacarbonyldimanganese(O) complex, Mn2(CO)10, has been evaluated as a catalyst for hydrosilylation reactions of 1-hexene with tertiary silanes, Et3SiH and (EtO)3SiH. The reaction of Et3SiH appears to be first order with respect to the catalyst, to the hexene and to the silane, although catalyst deactivation occurs when relatively high silane concentrations are used. The reaction rate is slightly affected by varying the type of the silane used. The rate of disappearance of the tertiary silane is consistent with that of the 1-hexene, which means that the catalyst is selective to hydrosilylation reactions. This was confirmed by following the rates of disappearance of Si-H and C=C IR bands at 2210, 2100 and 1650 cm−1 for (EtO)3SiH, Et3SiH and 1-hexene respectively. A comparison of the behaviour of Mn2(CO)10 with that of Co2(CO)8 is reported here, together with a suggested mechanism for the manganese catalyst.