Euripides was born on the 1st of March, 1938 in Ponce, Puerto Rico, where he grew up and went to school. At the age of 18, he joined the US Army at Fort Buchanan in Puerto Rico and within ten years, he was a Captain with the 1st Infantry Division and deployed to the Republic of Vietnam. It was his actions on the 8th of November, 1966, during Operation Attleboro, that would earn him the Medal of Honor. The citation reads:

For conspicuous gallantry and intrepidity in action at the risk of his life above and beyond the call of duty. Capt. Rubio, Infantry, was serving as communications officer, 1st Battalion, when a numerically superior enemy force launched a massive attack against the battalion defense position. Intense enemy machinegun fire raked the area while mortar rounds and rifle grenades exploded within the perimeter. Leaving the relative safety of his post, Capt. Rubio received 2 serious wounds as he braved the withering fire to go to the area of most intense action where he distributed ammunition, re-established positions and rendered aid to the wounded. Disregarding the painful wounds, he unhesitatingly assumed command when a rifle company commander was medically evacuated. Capt. Rubio was wounded a third time as he selflessly exposed himself to the devastating enemy fire to move among his men to encourage them to fight with renewed effort. While aiding the evacuation of wounded personnel, he noted that a smoke grenade which was intended to mark the Viet Cong position for air strikes had fallen dangerously close to the friendly lines. Capt. Rubio ran to reposition the grenade but was immediately struck to his knees by enemy fire. Despite his several wounds, Capt. Rubio scooped up the grenade, ran through the deadly hail of fire to within 20 meters of the enemy position and hurled the already smoking grenade into the midst of the enemy before he fell for the final time. Using the repositioned grenade as a marker, friendly air strikes were directed to destroy the hostile positions. Capt. Rubio's singularly heroic act turned the tide of battle, and his extraordinary leadership and valor were a magnificent inspiration to his men. His remarkable bravery and selfless concern for his men are in keeping with the highest traditions of the military service and reflect great credit on Capt. Rubio and the U.S. Army.

Euripides would posthumously receive the Medal of Honor in 1968 and there would be several buildings named in his honor: The US Army Reserve Center in San Juan, Puerto Rico; the US Department of Veterans Affairs Outpatient Clinic in his hometown of Ponce; the American Legion Post 142 in San Juan. His name would also be inscribed on El Monumento de la Recordacion at the front of the capitol building in San Juan, as well as on Panel 12E, Row 044 of the Vietnam Veterans Memorial wall in Washington DC. Euripides Rubio Jr was 28 years old when he died. He is one of nine Puerto Rican Medal of Honor recipients and he is buried in the Puerto Rico National Cemetery in Bayamon: Section HSA-5.