Your coworker left the company or was terminated, and now he is asking for a reference letter from you. If this is your first time writing an employment reference letter, be aware of the intricacies involved in reference-letter writing. Technical guidelines must be followed or else the individual being referred may not have a great chance at the prospective job opportunity. When you get the phone call from your ex-coworker, find out when he needs the letter so that you can manage your time and get it written by the deadline.

Structure your reference letter the way you would any business correspondence. That is, type the addressee's name on the left side of the page. Or, you may write "To Whom it May Concern" or if you do not know the addressee's name. Sometimes, job applications will tell applicants to submit the reference letter to a particular department, such as Human Resources. This information should be provided by your former colleague.

Open the letter by explaining who you are and how you know the individual being referred. Since he is your ex-coworker, write about the capacity in which you worked together. For instance, if you were part of the same department, say so. Or if you worked in separate departments, but had to collaborate on projects, let the reader know. This gives you credibility as a reference. If you have specific information, such as you worked together for three years, add that in the opening paragraph.

Start a second paragraph. Write about your former coworker's personal characteristics, such as dependability, loyalty, motivation and good organizational skills. The characteristics you name should be positive, since this is a letter of recommendation.

Discuss your ex-coworker's work-related strengths. If he did a great job managing projects, working in teams, developing new policies or being innovative, say so. Give concrete examples. Also include information about any awards he received for outstanding work, if applicable. Put this information in the second paragraph.

Wrap up the reference letter with a closing paragraph. This paragraph is reserved for your personal recommendation of him as a candidate for future job opportunities. Say that you recommend the individual, think he would be an asset to the organization and that you strongly encourage him being hired.

Sign the letter with your signature, and include your contact information at the bottom in case they want to contact you for a phone reference, too.