HISD said the buses were parked at the Northwest Motor Pool on Pinemont over the Thanksgiving holiday when the parts were stolen.
No arrests have been made, the district said.
HISD said 14 routes were impacted and substitute vehicles are currently taking kids to and from school.
A new ordinance to crack down on catalytic converter thefts and resale went into effect across Houston over the summer.
It requires individuals to show proof of owning a cut catalytic converter when they go to sell it to a metal recycler.
SEE ALSO:
Catalytic converter ordinance in effect after rise of thefts in Houston
Ordinance in effect after rise of catalytic converter thefts
Authorities find Houston-area ties in nationwide crackdown on catalytic converter theft
Authorities find local ties in nationwide crackdown on catalytic converter theft
5 suspects arrested in catalytic converter theft ring are tied to deputy's murder, officials say
Arrests in theft ring bust are tied to deputy's murder, officials say