We bathed Pep when he was 19 - if you have a sink with a spray faucet, that works, or just very gently in the bathtub - fill it with some warm water and shampoo and put him in it and reassure him the whole time. That's what worked for us. Then be sure to dry him completely - we used a hair dryer on low setting and lots of towels - cat hair seems to really hold water. Good luck!