This study is being conducted to comply with the Food and Drug Administration (FDA) recommendation that all new non anti-arrhythmic drugs be assessed for cardiac repolarization effects through electrocardiographic evaluation. Therefore, this study will evaluate the effect of GSK1265744 on cardiac conduction as assessed by collection of twelve-lead continuous digital data in healthy adults. This study will evaluate the effect of three doses of GSK1265744 on the QT duration corrected for heart rate (QTc) interval as compared to placebo. Moxifloxacin will be used as a positive control in order to validate the sensitivity of the study in detecting QTc change. This study consists of three treatment periods (each separated by 21 day washout period) followed by follow-up visit 10 to 14 days post last dosing. The total duration of study including follow-up visit will be approximately 62 days. Approximately 42 subjects will be enrolled such that 34 subjects complete dosing and critical assessments.

Inclusion Criteria:

• Male and females aged between 18 and 55 years of age inclusive, at the time of signing the informed consent.
• Healthy as determined by a responsible and experienced physician, based on a medical evaluation including medical history, physical examination, laboratory tests and cardiac monitoring.
• Body weight >=50 kilograms (kg) for men and >= 45 kg for women and body mass index (BMI) within the range 18.5-31.0 kg/meter^2 (inclusive).
• A female subject is eligible to participate if she is of: non-childbearing potential defined as pre-menopausal females with a documented tubal ligation, bilateral oophorectomy or hysterectomy [for this definition, "documented" refers to the outcome of the investigator's/designee's review of the subject's medical history for study eligibility, as obtained via a verbal interview with the subject or from the subject's medical records]; or postmenopausal defined as 12 months of spontaneous amenorrhea [in questionable cases a blood sample with simultaneous follicle stimulating hormone (FSH) > 40 milli international unit (MlU)/mililiter (m) and estradiol < 40 picogram/mL (<147 picomoles/L) is confirmatory] OR has only same-sex partners, when this is her preferred and usual lifestyle.
• Male subjects with female partners of child-bearing potential must agree to use one of the contraception methods. This criterion must be followed from the time of the first dose of study medication until 21 days post-last dose.
• Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.

Exclusion Criteria

• Current or chronic history of liver disease, or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).
• History of regular alcohol consumption within 6 months of the study defined as: an average weekly intake of >14 drinks for males or >7 drinks for females. One drink is equivalent to 12 grams of alcohol: 12 ounces (360 mL) of beer, 5 ounces (150 mL) of wine or 1.5 ounces (45 mL) of 80 proof distilled spirits.
• History of sensitivity to heparin or heparin-induced thrombocytopenia.
• History of sensitivity to any of the study medications, or components thereof or a history of drug or other allergy that, in the opinion of the investigator or GlaxoSmithKline (GSK) Medical Monitor, contraindicates their participation.
• A positive pre-study Hepatitis B surface antigen or positive Hepatitis C antibody result within 3 months of screening.
• Use of tobacco- or nicotine-containing products within 6 months prior to screening.
• A positive pre-study drug/alcohol screen.
• A positive test for human immuno virus antibody.
• Subjects with an alanine aminotransferase, alkaline phosphatase and bilirubin >=1.5xupper limit of normal (ULN) (isolated bilirubin <1.5xULN is acceptable if bilirubin is fractionated and direct bilirubin >35%).
• The subject's systolic blood pressure is outside the range of 90 to140 milimeter of mercury (mmHg) or diastolic blood pressure is outside the range of 45 to 90mmHg or heart rate is outside the range of 50 to 100 beats per minute (bpm) for female subjects or 45 to 100 bpm for male subjects.
• Exclusion criteria for screening ECG (a single repeat is allowed for eligibility determination): are: male subjects with Heart rate <45 and >100 bpm and female subjects with heart rate <50 and >100 bpm, PR <120 and >220 milliseconds (msec), QRS duration <70 and >120 msec, QTcB >450 msec.

Evidence of previous myocardial infarction (Does not include ST segment changes associated with repolarization).

Any conduction abnormality (including but not specific to left or right complete bundle branch block, atrioventricular block [2nd degree or higher], Wolf Parkinson White syndrome).

Sinus Pauses > 3 seconds. Any significant arrhythmia which, in the opinion of the principal investigator and GSK medical monitor, will interfere with the safety for the individual subject.

Non-sustained or sustained ventricular tachycardia (>=3 consecutive ventricular ectopic beats).

• Where participation in the study would result in donation of blood or blood products in excess of 500mL within a 56 day period.
• The subject has participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer).
• Exposure to more than four new chemical entities within 12 months prior to the first dosing day.