The objective of this work is to measure space and time resolved heat transfer variations during nucleate pool boiling of R113/R11 mixture using a micro-scale heater array in conjunction with a high speed CCD. The micro-scale heater array is constructed using VLSI techniques, and consists of 96 serpentine platinum resistance heaters on a transparent quartz substrate. Electronic feedback loops are used to keep the temperature of each heater in the array at a specified value, and the variation in heater power required to do this is measured. Heat flux data around an isolated bubble are obtained with triggered CCD images. CCD images are obtained at a rate of 1000 frames/second. The heat transfer variation vs. time from the heaters directly around the nucleation site is plotted and correlated with images of the bubble obtained using the high speed CCD. For both of the mixture and pure system, the growth rate of the bubble and heat fluxes are presented and compared in visual and quantitative view points.