• capital city of equatorial guinea malabo is the capital of equatorial guinea and its largest city. it is on the island of bioko (fernando p?o) and was formerly known as santa isabel. population: 37,500 (1992). malabo is the capital of equatorial guinea and its largest city. it is on the island of bioko (fernando p?o) and was formerly known as santa isabel. population: 37,500 (1992). malabo is the capital of equatorial guinea and its largest city. it is on the island of bioko (fernando p?o) and was formerly known as santa isabel. population: 37,500 (1992). malabo is the capital of equatorial guinea and its largest city. it is on the island of bioko (fernando p?o) and was formerly known as santa isabel. population: 37,500 (1992). malabo is the capital of equatorial guinea and its largest city. it is on the island of bioko (fernando p?o) and was formerly known as santa isabel. population: 37,500 (1992).