Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large mixing bowl, cream together the butter, white sugar, and brown sugar until smooth.
Beat in the eggs one at a time, then stir in the vanilla.
Combine the flour, cocoa, baking soda, and salt; gradually stir into the creamed mixture. Mix in the chocolate chips.
Drop by rounded spoonfuls onto the prepared baking sheets.
Bake for 8 to 10 minutes in the preheated oven, until cookies are set. Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.