Inclusion Criteria:

1. Be smokers motivated to reduce their cigarette usage but not seeking treatment to quit smoking at the time of screening.
2. Be Able to give written informed consent after being presented with an IRB-approved informed consent document
3. Be male or female of any race, between eighteen and sixty five years of age.
4. Be in stable physical and mental health as judged by interview
5. Be smoking 10 or more cigarettes per day for one or more years
6. Have an expired CO reading of ≥10 parts/million prior to beginning study
7. Test non-pregnant and use adequate birth control (female only). All female subjects will have a urine pregnancy test performed prior to the first dose of study medication.
8. Be able to comply with protocol requirements and be likely to complete all study treatments.
9. Live within 50 miles of the study site

Exclusion Criteria:

1. Have current dependence, defined by DSM IV criteria, on any psychoactive substance other than nicotine, alcohol, or marijuana or physiological dependence on alcohol requiring medical detoxification.
2. Have a history of significant hepatic, renal, endocrine, cardiac (i.e., arrhythmia requiring medication, angina pectoris, myocardial infarction,), stroke, seizure, neurological, non-drug-related psychiatric, gastrointestinal, pulmonary, hematologic or metabolic disorders.
3. Have a history of adverse reaction/hypersensitivity to N-acetylcysteine.
4. Have any significant active medical or psychiatric illness (e.g. schizophrenia, suicidal/homicidal ideation within the past 30 days) which might inhibit their ability to complete the study or might be complicated by administration of NAC.
5. Used carbamazepine or Nitroglycerin within the last 14 days or any other medication felt to be hazardous if taken with NAC
6. Have a current or past history of asthma and/or the occasional or daily use of Albuterol or other beta-agonist inhalers.
7. Females pregnant or breast-feeding
8. Have any medical history or condition considered by the investigator(s) to place the subjects at increased risk.
9. Not fail to actively meet the inclusion criteria at the time of screening.
10. Have a history of childhood or adult seizures of any cause.
11. Be currently taking any medications (i.e., beta-blockers, stimulant medications) that might affect heart rate or skin conductance