Abstract: This invention is a process for the preparation of para-bromo-phenole derivatives of the formula I ##STR1## wherein R.sub.1, R.sub.2 R.sub.3, R.sub.4 and R.sub.5 each independently represents hydrogen or lower alkyl radical of 1 to 6 carbon atoms, characterized in that a phenol derivative of formula II ##STR2## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are as defined above, is reacted in the presence of a solvent with a compound of the formula ##STR3## or with bromine and a compound of the formula IV ##STR4## wherein R.sub.6 and R.sub.7 in the formulae III and IV being each independently a lower alkyl radical of 1 to 6 carbon atoms, an aryl radical or they form together with the S-atom to which they are attached, a 4 to 6 member ring.