Yes you can claim your son as a dependent as long as he did not provide more than half of his own support for the year, live with you, and meets the rest of the requirements for a qualifying child--relationship, age, residency, support, and joint return.

1.  Relationship - He's your son -- no problem there.

2.  Age - A child must be:

• Under age 19 at the end of the year; 
• A student under age 24 at the end of the year.   [According to IRS Pub. 501:   "To qualify as a student, your child must be, during some part of each of any 5 calendar months of the year… The 5 calendar months don't have to be consecutive."];
• Permanently and totally disabled at any time during the year, regardless of age.

3.  Residency - Your child must have lived with you for more than half the year. [Being away at college is still considered living with you (for tax purposes).]

4.  Support - The child can't have provided more than half of his or her own support for the year.

5.  Joint return - To meet this test, the child can't file a joint return for the year.

 If he does not meet the requirements of a Qualifying Child, you may claim him as a Qualifying Relative instead.  The requirements are listed page 17 of  IRS Pub. 501.