The Open Computing Language (OpenCL) is increasingly adopted for programming processors with reconfigurable hardware acceleration. The 5G telecommunication infrastructure, imposing strong latency constraints on the managed communications, may benefit from OpenCL-designed accelerated processing. This paper presents the first study to evaluate OpenCL hardware acceleration in the context of a 5G base station physical layer. The implementation and optimization process to accelerate the Orthogonal Frequency Division Multiplexing (OFDM) part of the 5G downlink is conducted on a high-end Field Programmable Gate Array (FPGA). We show that the proposed OpenCL implementation complies with the 5G processing timing requirements since the computation time is consistent with the present 5G deployment. However, to be suitable for 5G, the OpenCL platform must improve the data latency transfer between hardware and software. Moreover, a further enhancement for the OpenCL implementation is to improve the code by means of OpenCL optimization techniques. In this way, the performance can be further improved with respect to optimized software on vectorized high-end processors.