The title compound (quaternary ammonium salt: P-51 from Orient Chemical Industries, Ltd.) is a well-known charge-control agent (CCA) used widely in electrophotography. Structure analysis and electrical measurements have been carried out in the present investigation in order to study its high thermal stability as well as to give more experimental evidence for our charge-control mechanism that assumes an appreciable temperature increase at the "toner/carrier" interface. P-51 is found to crystallize in a space group of P2₁/n. Observed unexpectedly were chains of OH··O intermolecular hydrogen bonds between the OH group of one anion and the O atom of the other, leading to a polymerlike stabilization of P-51, as characterized by a high melting point. On the other hand, the electrical conductivity is shown to increase exponentially with temperature by 2 to 3 orders of magnitude in the temperature range between room temperature and 100° C. This supports out our charge-control mechanism.