In conventional nanoimprint lithography, relatively high pressures and high temperature are used for embossing thermoplastics. However, this may induce mechanical strain in the mold and sample, and prohibits patterning of fragile substrates. Polymer flow in the viscoelastic regime is quite a slow process that can also limit patterning performances. To overcome these difficulties, a low-pressure and moderate-temperature imprint process using a low-viscosity thermocurable epoxy-siloxane prepolymer is proposed. We demonstrate replicated patterns with 60 nm lines and 150 nm space, and less than 20 nm residual layer. The low-viscosity process also allows for the simultaneous replication of micrometer- and nanometer-scaled patterns. Transfer onto silicon substrate via reactive-ion etching or lift-off is possible without removing the residual layer. (C) 2005 American Vacuum Society.