I've been trying to get my husband into books. He is currently reading Rendevous with Rama by Arthur C Clarke and absolutely loves it. Before that he was attempting Hitchhiker's Guide and wasn't enjoying it. I think he likes Rama better because (according to him) it's more realistic and has suspense, but isn't overwhelming. I know there's lots of Arthur C Clarke books he can read (I'm getting the rest as he goes), but what other books could I introduce to him that he may like?
Other books he has liked in the past: 1984, The Good Earth, and Animal Farm.
I don't know if he would like anything about Adventure/exploration/mountaineering - but I have Into Thin Air by John Kraukauer available. Its a true story but about mountaineetring. Just a thought.
Have him try books by Michael Crichton. He wrote a number of books with science backgrounds There's always the Dirk Pitt series by Clive Cussler. Guys are usually okay with bugs; I guess I'm unusual because I love books by Tim Downs, particularly his bug man" series about a forensic entomologist (try "First the Living", a fictionalized account of people and body retrieval in New Orleans after Hurricane Katrins). Also, I would consider looking for bookss by Tom Cain; I think there are two so far, lots of suspense and action.