Abstract Excition surface polaritons (ESP's) have been detected by attenuated total reflection spectroscopy on three organic solids at room temperature. This is the first time that ESP's have been observed at room temperature on nay material. The three solids are: CTIP for γ-cyclopropylbis (1,3,3-trimethyl-indolenine-2-yl) pentamethinium fluoroborate. PTS for poly-2,4-hexadiyne-1,6-diol bis(p-toluene sulphonate) and TCNQ° for tetracynaoquinodimethane. These three materials are chemically very different, the first being an ionic crystal, and second a crystal of macroscopically long polymers, and the third a molecular crystal. The common property that allows all three to support ESP's is the existence of electronic transitions of very high intensity. These transitions have very wide polariton stop-bands within which one component of the dielectric tensor assumes negative values. This is a necessary condition for the existence of the surface polaritons.