Recommended translation: "Euthyphro" in Four Texts on Socrates,  trans. Thomas G. West and Grace Starry West (Cornell University Press: 1984, rev. 1998).  

About the dialogue:

Euthyphro (ca. 399 BCE) is a Socratic dialogue by Plato, set in the weeks leading up to Socrates’ trial and death. While awaiting a preliminary hearing near the king archon’s court, Socrates meets Euthryphro, and the two men discuss, among other things, the definition of piety. (Socrates has, of course, has been accused of the crime of impiety.)

Online:
Amazon (Recommended Translation)
Project Perseus (English, Free Access)
Project Perseus (Greek, Free Access)
Project Gutenberg (English, Free Access)