<b>Photothermal Boiling in Aqueous Nanofluids</b> The process of photo thermal evaporation in nanofluids finds promising applications in solar energetics, medicine and process technology. Previous studies report highly efficient production of solar steam in fluids with gold nanoparticles. In this article, we establish the process in nanofluids with less expensive carbon black CB and iron oxide IO nanoparticles NP . Screening the concentration of nanoparticles, we tailor the nanofluids to reach the efficiency maxima 66 at 3 wt. CBNP and 75 at 10 wt IONP the steam was superheated up to 10 K CBNP and 16 K IONP . It was also discovered that the IONPs generated steam was contaminated with nanoparticles. In addition to experimental results, we have developed an empirical model of photo thermal steam generation in nanofluids. The model agrees well with the experiments. solar steam, nanofluid, boiling, carbon black, iron oxide 1611-1617 Issue-5 Volume-2 D. Navilan