The adsorption of carboxymethyl cellulose (CMC) onto talc has been studied using particle film ATR FTIR. This approach allows for the in situ acquisition of vibrational spectra, i.e., acquired as the polymer is adsorbing from solution, enabling adsorption to be studied as a function of varying solution conditions. In this work, adsorption has been studied in the absence and presence of calcium ions, as well as under conditions of increased ionic strength of a simple electrolyte. Calcium ions have been implicated in the enhancement of adsorption of CIVIC on talc and an increase in the effectiveness of CIVIC as a talc depressant. The in situ spectra of the adsorbed polymer indicate clearly that CIVIC interacts chemically with the talc surface. In addition, the effects of ionic strength and the presence of Ca ions on the adsorption of the polymer were seen to be similar: they increased the adsorbed amount and altered the polymer conformation at the surface. (C) 2008 Elsevier Ltd. All rights reserved.