Abstarct: Boiling heat transfer is one of the most applicable heat transfer processes within the industry. In recent years, many researches have been investigated in nanofluids pool boiling field and reported some contradictory results. This research is a qualitative and quantitative investigation to understand the behaviors of nanofluids and nanocoated surfaces during pool boiling heat transfer. The pool boiling behavior of low concentration (≤1 gr/Lit) nanofluids have been studied experimentaly on a cooper flat heater that dispersed CuO nanoparticles in pure water. In this study the boiling surface is considered to be cooper flat surfaces with, 10mm diameter and surface roughness of Ra=7.5 nm. CuO-water nanofluids have been craeted by 40nm nanoparticles and 1 to 1000 (mg/Lit) of concentrations is used in this resarch. Repeatatability and accuraecy of set¬ up have been tested tree times for DI Water, indicating a sutable concordance with the traditional correlations. By investigating heat transfer coeficient and critical heat flux in different concentration of nanofluids, it is seen that heat transfer increases by enhancing concentration to 50 (mg/Lit) and decreases for further amount. Thus, for 50 (mg/Lit) concentration of nanofluid heat transfer coeficient has it's maximum amount wich is 50% improvement. Critical heat flux also decreases for higher concentration more than 100 (gr/Lit) and decreases as the concentration increase for lower concentration. Critical heat flux has improved 92% in optimised concentration with is 100 (gr/Lit) compared to DI Water. AFM, SEM and contact angle metods have been conducted for analysing properties of surface and nanocoated which are formed after nanofluids boiling. Results demonstrate that there is a positive effect in increasing roughness and a negetive impact of thickness enhancement on critical heat flux and also improvement in heat transfer coefficient. Also it is seen that the heat transfer coefficient increases as the surface hydrophobe increases. In this study high spead camera and image proccecing is used for investigating bubble hydrodinamic, and frequency analysis of departure and diameter of departed bubbles. It has been concluded that departed frequency in Cuo-water nanofluids is more than DI Water and diameter of bubble is less than DI Water.