ABSTRACT The continuous relaxation time spectrum was modelled from the mechanical spectrum of a xanthan aqueous solution both using the TA Instruments TRIOS® software, and with the rheology software IRIS®1 . Two types of calculation were applied to obtain the relaxation modes since the software bundles used in this study base the calculation upon two different algorithms, named “parsimonious” as it models continuous relaxation spectra using a minimum number of modes to obtain continuous relaxation times2 , and a nonlinear regularization method that provides a larger spectrum with several modes3 . The results were overall comparable but slightly different for long relaxation times.