PO4 may refer to:

• Phosphate
• PO4: an EEG electrode site according to the 10-20 system

• Wimaranga
• Wimaranga language
• Wimarshana
• WIMA SuperCap
• WiMAX 2
• WiMAX network
• Wim Balm
• Wimberley High School (Texas)
• WIMBIZ
• Wimbledon 1960
• Wimbledon 2016
• Wimbledon 2017
• Wimbledon 2018
• Wimbledon Art College
• Wimbledon Art School
• Wimbledon by-election, 1907
• Wimbledon by-election, 1916
• Wimbledon Championships 2016
• Wimbledon Championships - Ladies' Singles
• Wimbledon College of Art
• Wimbledon.com
• Wimbledon Cricket Club
• Wimbledon Garden Party (TV programme)
• Wimbledon Garden Party (TV Show)
• Wimbledon HC