That is pretty high. However don't assume that all bounces are bad. A bounce can actually be an indication that your site has done it's job well - it's down to the intent of the user.
I prefer to look at bounce rates either by page or by term. If people are bouncing on terms that are likely to have commercial intent then that isn't great. However for informational searches it might mean that the site is answering their query. That strong content might be the cause - you're becoming a reference site. Not necessarily bad.
However, bounces rarely pay bills... Try separating out searches with commercial and informational intent and compare both the volume and bounce rate. That might give some indication as to how best to tackle the issue (and what issue you are tackling).
If you have a high bounce rate on terms with commercial intent then look at the quality of your product information, pricing, issues around trust etc. If you can get outside opinion on it, even a small sample, that can help.
Conversely, if the problem is that you have an overly large proportion of research only terms then if could be that you need to look at how to increase visibility on the more commercial terms, or possibly look at ways to turn those information seekers in to customers (check loyaly and visits to purchase... they might be already, but just taking their time).
Pretty big topic actually.