Abstract This paper presents the requirements specification of artificial muscles based on smart materials for a robotic finger prosthesis. The first part introduces the robotic finger, designed to mimic human precision grasping. A methodology to determine three critical parameters (strain, frequency and force) is presented. The methodology uses experimental data combined with kinematics and dynamics. Obtained values are calculated using the developed finger; as a result, we define that main requirements are: (i) Minimum active strain 5.5% for extension-based actuation or 60% bending-based actuation, (ii) Frequency (8.89 Hz, 22.2 Hz), and (iii) Force (4.80 N, 6.74 N) for bending-based actuation or force (17.81 N, 25.11 N) for extension-based actuation. Finally, a review of smart materials is presented with the aim of choosing the group of materials that can be used as artificial muscles for robotic hands. We show that shape memory Alloys can fulfill the established specifications. We also stand out Ionic polymer metal composites as a very promising actuation solution for robotic hands, due to their active strain and settling time, even though the blocking force is below the requirements.