We have examined the interfacial thermal conductance GK of single and multilayer graphene samples prepared on fused SiO2 substrates by mechanical exfoliation of graphite. By using an ultrafast optical pump pulse and monitoring the transient reflectivity on the picosecond time scale, we obtained an average value of GK of GK = 5000 W/ cm2 K for the graphene/ SiO2 interface at room temperature. We observed significant variation in GK between individual samples, but found no systematic dependence on the thickness of the graphene layers. © 2010 American Institute of Physics.