The Martin XP2M was a second prototype of the basic flying boat design first developed as the Consolidated XPY-1. That earlier aircraft had been produced by Consolidated to a US Navy design, but the Glenn L. Martin Company had then won the production contract with a lower bid. While the eventual P3M production aircraft would be very similar to the XPY-1, Martin also produced the XP2M prototype.
The XP2M used the same basic design as the XPY, but with the parasol wing much closer to the fuselage. The XP2M-1 was powered by three engines – two built into the leading edge of the wing (as on the Catalina) and a third above the wing (an arrangement that would also later be used by Consolidated on the first P2Y). This third engine did not improve the performance of the aircraft, and was soon removed. Tests continued with two engines, probably with the designation XP2M-2.