Good for you! That he is willing to place his trust and confidence in you speaks volumes. This will be a unique opportunity for you to promote and sharpen your skills.

As the two of your decide how to handle his absence, there are several issues you must clarify with him. Ask him the 3 most important things you should keep a watchful eye on, and the 3 things that are most important NOT to have happen. Knowing these 6 things alone should give you the key to success.

Ask if he wants to be contacted once a day, once a week or only in the case of an extreme emergency (and if so, where and when would be okay to call). If he does want to be contacted, find out the specific information he wants to get from you during each call.

Ask him to send a memo to all the people in his group/department and his superiors to legitimize your being the ad-interim boss during his absence.

Finally, if he has an assistant, begin to work with him/her now so you will have established some rapport before his departure.

We hope you will approach this opportunity with more excitement than fear! Your boss believes you are up to the task, and if you believe it too you will shine.