Precipitation　strengthening　was　investigated　in　dilute　Al-Er,　Al-Hf　and　Al-Er-Hf　alloys.　Combined　addition　of　0.045　at.%　Er　and　0.18　at.%　Hf　in　Al　gives　a　maximum　hardness　of　640　MPa,　which　is　significantly　higher　than　that　of　the　Al-0.　18Hf　and　Al-0.045Er　alloys.　The　remarkable　strengthening　can　be　attributed　to　the　addition　of　Er,　which　accelerates　the　precipitation　kinetics　and　stimulates　the　decomposition　of　Al-Hf.　The　effect　of　Er　and　Hf　on　precipitation　strengthening　in　Al-Er-Hf　alloys　is　discussed.　(C)　2014　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.