The goal of thermal ablation is to destroy cancerous cells by increasing the temperature of the target tissue. Among the ablative techniques, radiofrequency (RF) ablation is the most widespread since it can be used in both percutaneous and surgical settings, in safety and with relative ease of use. However, efforts to optimize the RF treatment are needed, considering that the size of necrotized lesions remains a central issue in the application of the ablative procedure. In this work we aimed to evaluate the temperature distribution around the RF probe during radiofrequency ablation (RFA) of ex-vivo animal livers. Temperature maps in the ablated area are obtained by equipping a commercial RF probe with 27 Fiber Bragg Grating sensors (FBGs). The experiments demonstrate the ability of the proposed setup to conduct multi-point measurements in tissues undergoing RFA and the dependence of temperature and thermal damage on insertion depth of the RF probe.