Positron emission tomography (PET) is an important clinical tool, and with its longer half-life, copper-64 has several unique attributes that make it a multi-purpose radionuclide with many potential applications. Additionally, copper as a trace element plays a pivotal role in several human metabolic and pathologic diseases and is involved in malignant cells biochemistry pathways. This offers the opportunity for scientists to explore the theranostic capabilities of copper-64. This current publication, arising from an IAEA Coordinated Research Project, describes the biochemical and radiopharmaceutical aspects of copper-64, and its clinical applications, with specific guidelines and methods for the production of copper-64 chloride, peptide and monoclonal antibody radiopharmaceuticals. It is expected to be of use to all professionals involved in the field by specifying ideal production, formulation and quality control methods.