Fluoroelastomer (FKM) rubbers are used in many demanding applications due to their ability to resist the attack of heat, chemicals, and solvents. Chemical crosslinking is known to have a major impact on the final product’s physical properties, thus the determination of crosslink type and quantity is extremely important for understanding material properties. In this investigation, a peroxide curable FKM terpolymer containing 67 wt% of fluorine was used. Triallyl isocyanurate (TAIC) was employed as peroxide coagent and its levels were varied from 1 to 5 phr in order to induce a crosslink density gradient. Experimental analysis was undertaken using rheometry, hardness, stress-strain (Mooney-Rivlin), equilibrium solvent swell and low field nuclear magnetic resonance (NMR) using the double quantum (DQ) technique. Increasing the concentration of TAIC coagent caused a systematic rise in rheometry torque, hardness and tensile strength while both elongation at break and swelling levels decreased. These results are concurrent with an enhanced overall level of crosslinking. This trend was confirmed by the steady increase observed by Mooney-Rivlin C1 and C1 + C2 values with increasing coagent concentration. The DQ NMR technique through use of fast Tikhonov regularization (ftikreg) was particularly useful in discerning the inhomogeneous nature of the compound morphology by detection with both the hydrogen and fluorine probes. The spatial distribution of the crosslink density suggests that the compound consists of small highly polymerized TAIC domains imbedded within the elastic crosslinked matrix. The optimal concentration of TAIC coagent was 3 phr according to compression set test results.