For an early risk assessment of chemical processes on pilot plant scale a worst-case approach has been chosen in order to focus on critical safety issues. The main risks in terms of thermal risk, gas evolution, material properties and increased reactivity are classified based on the "chemistry" only, before the intended pilot plant equipment is defined exactly. This enables a timely modification of the chemical process if significant risks endanger its feasibility on pilot plant scale. Prior to the first pilot plant batch a final compatibility check of the "chemistry" and the selected pilot plant equipment is necessary to ensure that the design limits would not be exceeded in case of a worst-case scenario. Two case studies are presented which show specific safety challenges. It is demonstrated how even significant risks can be controlled sufficiently on pilot plant scale by taking appropriate safety measures. (C) 2008 Elsevier Ltd. All rights reserved.