An　innovative　photoelectric　technology　is　presented　in　this　paper　for　detecting　frost　in　the　field　of　defrost-control　of　refrigerator　or　freezer　applications.　Experiments　were　conducted　with　a　small-scale　laboratory　test　section　under　natural　convection　conditions.　Two　agreeable　properties　of　the　new　technology,　＂on-off＂　and　＂linear＂,　have　been　demonstrated　by　the　experiments.　The　first　property　provides　an　effective　judgment　of　the　defrost-control　strategy　while　the　second　one　is　suitable　for　developing　an　accurate　measurement　of　the　frost　height.　The　characteristics　(electric　current,　environment　temperature,　metal　surface　temperature,　light　intensity　and　sensor　location)　that　affect　the　properties　were　investigated　for　the　development　of　this　technology.　(C)　2009　Elsevier　Ltd　and　IIR.　All　rights　reserved.