PKA may refer to:

• Napaskiak Airport (IATA code), airport in Napaskiak, Alaska
• Professionally known as:
  • Pen name
  • Stage persona
• pK_a, the symbol for the acid dissociation constant at logarithmic scale
• Protein kinase A, a class of cAMP-dependent enzymes
• Pi Kappa Alpha, the North-American social fraternity
• Public key authentication, establishing key authenticity in public-key cryptography
• Professional Karate Association
• Primary knock-on atom, an atom that is displaced from its lattice site by irradiation
• Painkiller Already, a podcast featuring FPSRussia
• Pentax K_A-mount, a camera lens mount

• The Latin letters PKA are visually similar to the Cyrillic acronym РКА, the Russian Federal Space Agency