342EDO is the equal division of the octave into 342 parts of 3.50877 cents each (dividing the steps of 171EDO in half). It is a very strong 11-limit system; not until 1848 do we reach one with a lower 11-limit relative error. It is, as one would expect, distinctly consistent through the 11-limit, but goes no higher; nonetheless, it is a zeta peak edo. A basis for the 11-limit commas is 2401/2400, 3025/3024, 4375/4374 and 32805/32768. It is the optimal patent val for 11-limit hemitert temperament, and supports hemiennealimmal.