In this paper we consider the problem of scheduling, on a two-machine flowshop, a set of
unit-time operations subject to time delays with respect to the makespan. This problem is
known to be \hbox{${\cal NP}$}𝒩𝒫-hard in the strong sense. We propose an algorithm based
on a branch and bound enumeration scheme. This algorithm includes the implementation of
new lower and upper bound procedures, and dominance rules. A computer simulation to
measure the performance of the algorithm is provided for a wide range of test
problems.