Spastic Cerebral Palsy is the most common type of Cerebral Palsy (CP) that affects muscle coordination and control. Using Radiofrequency Ablation (RFA) to target the motor branches of the median and ulnar nerve may provide an additional treatment to Botulinum Toxin for spasticity in the hand. However, there are a limited number of studies that report the use of RFA in treating upper-limb spasticity. This prompts the need to establish a simulation model that has been tested against physical phantom to help determine the efficacy of RFA as a treatment for spasticity. In this study, a 3D COMSOL Multiphysics model of a commercial RF probe was validated against a Thermochromic Liquid Crystal (TLC) homogeneous gel phantom. The results of the COMSOL model were compared to the TLC phantom in terms of temperature (0.42 ± 1.06°C for the TLC high temperature range and -1.90 ± 0.88°C for the TLC low temperature range), lesion shape (14.5 ± 5.0%) and lesion size (0.18 ± 0.06 mm). These results show that COMSOL Multiphysics may be feasible as a tool to characterise RF lesions if the reported errors are accounted for. Further work is required to develop a more complex COMSOL model that incorporates different tissue aspects. However, this is a first step to establishing a validated COMSOL model of a RF probe in homogeneous muscle tissue.