PKA, pKa, or other similar variations may stand for:

  • pKa, 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
  • Professionally known as