After Zimbabwe won the toss and elected to bat, Masakadza reached 101 not out from 171 balls with nine fours and two sixes. He will resume on Monday with Sikandar Raza (nine not out).
Masakadza watched from the opposite end as Zimbabwe slipped into early trouble when they limped to 14 for three as West Indies seamer Kemar Roach (two for 24) made early inroads for the visitors, including the big wicket of Brendan Taylor (one).
But Masakadza, who scored his fifth test century, put on 142 for the fourth wicket with Peter Moor (52) before the latter was bowled by Roston Chase (one for 26).
The players left the field at the end of the 61st over and persistent rain kept them off for the remainder of the day.
West Indies won the first test by 117 runs and cannot lose the two-match series.
(Reporting By Nick Said; Editing by Clare Fallon)
