Different ancient mortar samples of Pamplona cathedral have been analysed to characterize their binder and aggregate fractions. A complete characterization has been carried out including chemical (complete macrochemical analysis, analysis of the soluble fraction in hot HCl (1:5) and of the insoluble residue, trace elements and soluble salts, using traditional chemical procedures, ion chromatography and spectrophotometry techniques), mineralogical (structural characterization, granulometric studies and X-ray diffraction) and thermal studies (simultaneous DTA and TG analysis). A lime binder with a silica aggregate has been established. The approximate original compositions of the classes of mortars have been determined using the TG results. A good agreement with the other characterization techniques has been showed by the thermoanalytical techniques. An incomplete carbonation in a sample has been discovered by the thermal analysis.