A composition comprising: (1) a susceptor of magnetically coupled radio frequency energy comprising a non-magnetic particulate substrate, e.g., an electrically insulative material in particulate form, bearing a thin magnetic coating, e.g., a magnetic inorganic film, and (2) a matrix that is substantially non-reflective of radio frequency energy, e.g., silicone rubber, which matrix can be heated upon the composition's being subjected to magnetically coupled radio frequency energy. It has been discovered that thin magnetic coatings on non-magnetic particles provide energy transfer with induction heaters equal to or better than many commonly used solid susceptor particles. It has also been discovered that the temperature of the composition of this invention can be regulated so as not to exceed a predetermined temperature.