Dosimetric intercomparison in the core of the ISIS reactor is performed using two different types of calorimeters: a pedestal differential device designed at CEN Saclay (France) and a heat-flow calorimeter designed at the Boris Kidrič Institute of Nuclear Sciences (Yugoslavia). The results obtained in graphite and polyethylene as reference materials are intercompared for both types of calorimeters and an agreement within a few per cent obtained. From the neutron measurements, the neutron dose rates are calculated and compared to the values derived from calorimetry; the agreement within 15% is obtained. Several chemical dosimetric systems (i.e., oxalic acid dissolved in light and heavy water, solid oxalic, malonic, and succinic acid) were irradiated and the curves of dose effect obtained.