The objectives of this study are to develop frost maps for two different surfaces having two different hydrophilic characteristics and to find ambient conditions associated with the formation of frost structures. Test samples with two different surfaces having dynamic contact angle (DCA) of 23degrees and 88degrees were installed in a wind tunnel and exposed to a humid airflow. Frost structure is observed with a visualization system in the operating conditions of household refrigerator: airflow temperature in the range of +10-20 degreesC, humidity in the range of 2.64-9.36 g/kg', Reynolds number in the range of 7000-17,000 and cold plate temperature in the range of -11.6 to -28.4 degreesC. As results of this study, frost structures are classified and frost maps are proposed for two different surface hydrophilicities. Surface with low DCA (23degrees) shows lower frost thickness and higher frost density than that with high DCA (88degrees). It was found that frost structures on surfaces with different DCA are similar. However, low DCA surface at low humidity provides 20-30% denser frost formation due to the shift of areas with different structures. (C) 2004 Elsevier Ltd. All rights reserved.