We report the synthesis of silver nano-crystals (Ag-NCs) composited bismuthate glasses through a single-step thermal reduction approach. The Ag-NCs show broad surface plasmon resonance (SPR) absorption bands with spectral coverage from visible to near infrared region. Bi2O3 is found to be the key factor to the formation of Ag-NCs, e.g. their number density varies significantly and the corresponding SPR red-shifts as Bi2O3 content increased. Third-order optical nonlinearities (TON) of the silver-bismuthate nanocomposites were investigated by Z-scan and pump-probe techniques at the wavelength of 800 nm. The experimental results revealed SPR-assisted behavior and ultrafast temporal response (less than 100 fs) of TON properties of the nanocomposites. (C) 2013 Elsevier Ltd. All rights reserved.