The heat transfer coefficient is a crucial parameter with regard to safety in the execution of exothermic reactions in production scale. The process-side heat transfer coefficients in small-scale rectangular channels equipped with various static mixing elements were determined experimentally and their dependence on flow rate of the process fluid, geometry and thermal conductivity as well as on the cross-section of the channel was investigated. In comparison to an empty channel, inserts of any kind lead to an increase of the heat transfer coefficient due to forced convection.