Thomas Aquinas' commentary on Aristotle's Perihermenias (also known as the De Intepretatione) was probably  written between 1269 and 1271, following his other 'Aristotelian' commentaries such as the Posterior Analytics (1268) and the Metaphysics. There are some notes on the Perihermenias, together with links to other commentaries (including this one) here. Geach  dismisses the work. "Aquinas was not much interested in formal logic for its own sake, as many medieval philosophers were; he never bothered to finish his commentary on the De Interpretatione (and what there is of his commentary is of little intrinsic interest, apart from the passage on future contingents) and he never commented on the Prior Analytics at all". Note that the passage on future contingents begins at lecture 13, referring to Aristotle's chapter 9 - although the work is a bit more interesting than Geach suggests.
As Geach notes, the work was never finished, ending after Book II, Lesson 2. This may have been because he 'never bothered', it may also be because he died shortly afterwards in 1274, without having finished his monumental Summa Theologiae. It was finished by Cajetan in 1496, and first published at Venice in 1496 as Expositio in Libros Posteriorum et in De Interpretatione.)
The commentary includes links from the incipits to a Boethius' translation from the Greek into the Latin, in parallel with Edghill's English translation from the Greek.
The Latin is taken from the Taurini edition, the English from the translation by J.T. Oesterle, (Mediaeval Philosophical Texts in Translation 11, Milwaukee, WI: Marquette University Press, 1962).
Edward Buckner, November 2010
 Geach. P., Logic Matters, Blackwell 1972, ch. 10, p. 300
THE LOGIC MUSEUM II