Abstract :
An estimate for Hecke Zeta-functions with Grössencharacters on the critical line is proved which corresponds to the classical resultζ(1/2+it)much less-thanvar epsilon(t+1)1/6+var epsilonon Riemannʹs zeta-function. The constants implied in the much less-than-sign depend neither on the conductor nor on the exponents of the Grössencharacter.