The electrothermal atomic absorption spectrometric determination of bismuth, indium and lead in geological samples and synthetic sea water has been carried out by using nickel-containing chemical modifiers. A comprehensive comparison was made among the nickel-containing modifiers such as Ni, Ni+Pd, Ni+Rh, Ni+Pt and Ni+Ru. In addition to that, tartaric acid (TA) was used as a reducing agent together with the above-mentioned mixed modifiers. Comparison was made in terms of pyrolysis temperature, atomization and background absorption signal shapes, and accuracy of the determination. The modifier mixtures of Ni+Pd+TA and Ni+Pt+TA were found to be preferable for the determination of analytes because they increased the pyrolysis temperatures up to 1200-1400 degrees C. Depending on the geological sample type, the percent relative error was decreased from 20.0 to 0.6 for Bi and from 11.9 to 0.4 for Pb by using the proposed modifier systems. The accuracy of the determination of analytes in the synthetic sea water also increased. (C) 1999 Elsevier Science B.V. All rights reserved.