Phase transitions of pure substances provide the key reference temperatures, otherwise known as "defining fixed points", of the International Temperature Scale. At temperatures below the triple point of mercury (234.3156 K), the substances involved are gases at room temperature and include the triple points of hydrogen (13.8033 K), neon (24.5561 K), oxygen (54.3584 K) and argon (83.8058 K). The Consultative Committee for Thermometry also provides a list of "secondary reference points" whose quality approaches (or is equivalent to) that of the defining fixed points of the ITS Here, we report direct measurements of the triple point of krypton on the ITS-90, review the historical measurements that CCT WG2 relied upon for its 1996 assessment, and demonstrate that the triple point of krypton is a "first quality" secondary reference point. Based on our measurements, the temperature of the triple point of krypton is 115.7755 K ± 0.3 mK (k=1).