Chemically pure mono-dispersed spherical bismuth (Bi) nanoparticles (NPs) having diameter in the range of 5-20 nm are prepared by liquid pulsed laser ablation technique. The effect of ablation time and the surfactant (C12H25NaO4S) on the size of nanoparticles are studied and both were found to play crucial role in controlling the size of the NPs and consequently, the optical properties. An absorption band observed around 980 nm is attributed to semimetal to semiconductor transition. Interestingly, prepared semiconductor Bi NPs are found to generate intense heat when 976 nm laser wavelength falls on them and thus generates a hope for potential biomedical applications viz. hypothermia treatment. (C) 2012 Elsevier Inc. All rights reserved.