A direct technique for the measurement of jitter in a Josephson transmission line (JTL), which is similar to an approach used to measure complementary metal-oxide-semiconductor latch metastability, is presented. The experiment yields a one-sigma jitter value of 74 fs per JTL stage in 1 kA/cm2 rapid single flux quantum technology. The experimental configuration has been modeled with JSIM, and the result agrees with the experimental data. Additionally, an analytical model has been developed to assess the scaling of the jitter-to-stage delay ratio with critical current density of the Josephson junctions comprising the JTL. Finally, we compare the measured upper bound jitter per stage of a 65-nm complementary metal-oxide-semiconductor inverter chain with that of a 1 kA/cm2 JTL. © 2002-2011 IEEE.