In this study, an improved 2-D LIF/PTV technique is presented for the simultaneous measurement of temperature and velocity fields of cavity flows. 2-D Whole-Field temperature measurements are achieved by the two-color/two-dyes laser-induced fluorescence (LIF) technique, while the 2-D velocity is measured with particle tracking velocimetry (PTV) method. The improvements presented in this work is the modification of the commonly selected dyes to achieve the two-color LIF technique. Traditionally the organic dyes used to perform two-color LIF measurements are Rhodamine-B and Rhodamine-110, Rhodamine-B provides a fluorescence emission dependent on temperature while Rhodamine-110 provides an emission independent of temperature. In this work, Rhodamine-110 is replaced by Fluorescein-27, which provides a second temperature dependent dye. By using two temperature dependent dyes, the temperature sensitivity of the technique is increased. Also, in this work, a sensitivity analysis of the RHB-FL27 solution properties is presented, and its application to a natural convection two-phase flow within a cavity is explored.