Ratiometric laser induced fluorescence (LIF) thermometry technique has been quantitatively examined for its capability for a microscale field-of-view. The goal of the study is to quantitatively examine the measurement accuracy of the ratiometric LIF technique at sub-millimeter and micron scales for its potential use as a microscale temperature mapping tool. Measurements have been made for the steady temperature fields established by thermal buoyancy inside 1-mm wide closed test cell with low Grashof-Prandtl numbers (86 < Gr(w)Pr < 301), and the detailed measured data have been compared with the well-known predictions. The smallest measurement resolution could be achieved being equivalent to the CCD pixel size of 4.7 mum in the present experiment, but with large data uncertainties. The measurement uncertainties show persistent improvement to better than +/-1degreesC when measurement resolution is equivalent to 76 mum. (C) 2003 Elsevier Ltd. All rights reserved.