An electroless nickel plating bath comprising: i) a source of nickel ions; ii) an effective amount of thiourea; iii) an effective amount of saccharin; iv) a source of hypophosphite ions; v) one or more chelating agents; and vi) optionally, other additives and a method of using the same to provide a high phosphorus electroless nickel plating deposit on a substrate. The high phosphorus electroless nickel deposit is capable of passing an RCA nitric acid test, whereby the substrate with the high phosphorus nickel deposit thereon is immersed into concentrated nickel acid for 30 seconds and a deposit that does not turn black or grey is deemed to have passed the RCA nitric acid test.