Inclusion Criteria:

• Willing and able to sign an informed consent form.
• Men or women aged 18 years of age or older.
• A diagnosis of CKD and receiving peritoneal dialysis (CAPD, APD or CCPD) for 8 weeks or longer.
• In the opinion of the investigator, expected to receive peritoneal dialysis for the duration of the study.
• Will have a serum phosphorus level >1.76 mmol/L(5.50 mg/dL) after 2 weeks washout from their usual phosphate binder.
• Will have serum calcium measurement adjusted for albumin within the range (2.10-2.60 mmol/L (8.40-10.40 mg/dL) following 2 weeks washout from their usual phosphate binder.
• Willing to maintain the prescribed sevelamer or calcium acetate for the duration of the study.
• Considered compliant with phosphate binders and dialysis.
• On a stable doses of medication to treat hyperparathyroidism (Vitamin D or its analogues or calcimimetic agents) for the month prior to screening.
• Willing to discontinue use of antacids containing calcium, aluminium or magnesium at screening visit for the duration of the study (unless taken as an evening calcium supplement as prescribed by the investigator per protocol).
• Willing to avoid intentional changes in diet such as fasting or dieting.
• If female and of childbearing potential (pre-menopausal and not surgically sterile), willing to use an effective contraceptive method throughout study, which includes barrier methods, hormones, or IUDs.
• Have a level of understanding and willingness to cooperate with all visits and procedures as described by the study personnel.

Exclusion Criteria:

• Patients with a history of peritonitis in the last 30 days or > 2 episodes in the last 12 months
• Patient with active dysphagia, swallowing disorder, bowel obstruction, or severe gastrointestinal motility disorder.
• Patients who in the opinion of the investigator have poorly controlled diabetes mellitus, poorly controlled hypertension, active vasculitis, HIV infection, or any clinically significant, unstable medical condition.
• Patients with any evidence of active malignancy except for basal cell carcinoma of the skin. A history of malignancy is not exclusion.
• Current use of an antiarrhythmic medication such as quinidine, procainamide, tocainide, or amiodarone for the control of arrhythmias.
• Current use of a seizure medication such as phenytoin, phenobarbital, valproate, or carbamazepine for the control of a seizure disorder.
• Active ethanol or drug abuse, excluding tobacco use.
• If female, are pregnant, planning on becoming pregnant in the next 6 months or breast-feeding.
• Patients with a known hypersensitivity to sevelamer or any constituents of either study drug.
• Patients who have participated in a study of an investigational drug/device during the 30 days preceding the start of the screening period.
• Patients who have any other condition, which in the opinion of the investigator will prohibit the patient's participation in the study.
• Patient is unable to comply with the requirements of the protocol.