In a flow shop with two batch processing machines (BPMs) one of the key objectives is to minimise the makespan. In this study jobs with different sizes were batched together, without exceeding the machine capacity, and processed in the BPMs. Job ready times were also taken into consideration hence, a batch cannot be started unless all the jobs in the batch are ready and available. Also, the batches cannot wait between two machines (i.e., no-wait). The problem under study is NP-hard. A greedy randomised adaptive search procedure (GRASP) algorithm has been developed for this problem. Experiments were conducted to study up to 200 job instances. The solution quality of the GRASP algorithm was compared with the results of a mathematical model developed using CPLEX and a particle swarm optimisation algorithm. The experimental study highlights the advantages, in terms of solution quality of using GRASP to solve large-scale problems.