How much time do you have? The only loss of energy (loss of heat) will be by radiation. There is no conduction and of course no convection. Energy emission by radiation will be from black-body radiation (the emission of "light" energy that depends on the temperature of the body itself).

As temps decrease, the energy being emitted decreases, so the temperature of the body would approach but never really reach the limit of 0 contained thermal energy, although after a huge amount of time, it would be close enough that you couldn't measure the difference. The death of the universe condition (everything at absolute zero or, actually, slightly above because absolute zero is not possible for other reasons) is trillions of years in the future according to estimates I have seen (never tried to calculate it myself; not exactly certain how to).

There is a minor problem with your question, because the black body emissions can be absorbed too, so even in the absence of big energy sources like stars, all matter is being bathed in a low amount of energy, which would counter the loss by emissions, through absorption of radiation coming from other objects. Not much energy, certainly, but still energy. Also, there is a lot of energy zooming around which was emitted ages ago and has yet to interact with matter, and all matter will encounter some of that energy and heat up slightly by absorbing it.

The role of collisions and conversion of energy of motion (kinetic energy) to heat (or kinetic energy at the atomic level, which is pretty much what temperature is truly measuring) would lengthen that cooling process as well. Cannot have true absolute zero if things are moving.

Simple answer is that isolated matter in space does not cool to absolute zero (or as close to that state as can be attained by matter). Stuff in space is a bit warmer, a few degrees warmer in the sparser regions of space and considerably warmer if there is a decent source of emitted energy nearby. Still usually extremely cold by our human standards though, just not absolute zero.