A modified method for the calculation of liquid junction potentials based on the Henderson equation is proposed. The estimation of the activity coefficients and the conductivities is performed by means of the Modified Bromley Methodology [G. Borge, R. Castano, M.P. Carril, M.S. Corbillon, J.M. Madariaga, Fluid Phase Equilibria 121 (1996) 85-98; G. Borge, N. Etxebarria, L.A. Fernandez, M.A. Olazabal, J.M. Madariaga, Fluid Phase Equilibria 121 (1996) 99-109.] and the Extended Falkenhagen Equation [A. De Diego, Conductivity of concentrated electrolytic solutions : study of the dependence with concentration and temperature, Ph.D. Thesis, University of the Basque Country, Bilbao, 1996.]. The efficiency of the method has been tested in potentiometric titrations without constant ionic strength. Its applicability to potentiometric titrations with constant ionic strength is also discussed.