A rare occasion to investigate the conservation mode of the heart of the philosopher Voltaire (1694-1778) presented itself following an incident with his statue at the National Library of France which enclosed the organ. A multidisciplinary study was carried out to propose and implement an improved reconditioning method for the organ. The study generated a better knowledge of the fabrication technique of funeral metallic boxes as well as a better understanding of the degradation process of both the organ and the box. The heart and its conditioning, as well as the volatile products (VOCs) released by the heart were analysed with nondestructive methods. X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy associated with X-ray microanalysis (SEM-EDX) were used for the identification of the metal, the preparation and the gilding of the metal box. The heart-shaped metal box is made of lead with tin welds. The box received a double layer white lead preparation. The binding of the preparation is probably of proteinic nature. Gold leaf had been deposited on a gilding bole made of a mixture of red ochre and minium, enhancing the preciousness of this particular artefact. Identification of VOCs released from the heart done by SPME fibres followed by gas chromatography-mass spectrometry (GC-MS) analysis confirmed the origin of the strong smell, essentially acetic acid. From the inside of the heart-shaped metal box, emission of VOCs suggest that the organ may have been embalmed in a liquid containing alcohol (spirit of wine), resins, natural extracts or essences from cedar or lavender. Histological analysis of tissue samples showed the presence of striated muscle fibres. These results helped to determine the optimal reconditioning of the heart. It has been decided to keep the organ inside its metal box in a stabilized environment with static anoxia, in order to preserve the heart for future generations while protecting the tissues against oxygen degradation for further investigations.