Thugs smashed their way into properties before either threatening or dousing victims with a corrosive substance and fleeing.
The horrors unfolded at homes in Brent Cross, Wembley, Southall, Greenford between Wednesday and Friday.
The Metropolitan Police say the aggravated burglaries across West and North-West London are linked.
The suspects have been described as being dressed in dark clothing and donning balaclavas and gloves when carrying out the home invasions.
The menaces are also believed to be using a dark-coloured getaway car
No arrests have been made yet.
The first incident happened at around 11.14pm on Wednesday when four men forced entry into the propery. in Brent Cross and threatened a resident with a knife.
An unknown substance was thrown towards the victim, a woman aged in her 40s - it is unknown if any items were taken from the Highfield Avenue home.
Just 25 minutes later cops charged to an incident in Flamsted Avenue, Harrow, where four men smashed into a property and made off with jewellery.