OpenCL for GPU computing has been flying under the radar ever since CUDA became popular and the myth spread that it would more efficient. With the three major vendors, Nvidia, AMD and Intel, now all providing powerful data-center GPUs in the high-performance computing sector, it becomes more important than ever to be able to write GPU software once and deploy it on all supercomputers without wasting any time on porting. In this workshop, I will introduce OpenCL and highlight the significant benefits that OpenCL offers over other proprietary languages, in particular it’s excellent compatibility across all GPU hardware since 2009.