An apparatus (10) for preparing acetylene and synthesis gas by partial oxidation of hydrocarbons with oxygen is proposed, comprising a mixing unit (12), a mixing section and a mixing diffuser (16). The mixing unit (12) has a feed orifice (18) for supply of a hydrocarbonaceous stream, a feed orifice (20) for supply of an oxygenous stream, a swirl register and a distributor plate (24). The distributor plate (24) is disposed between the mixing section (14) and the feed orifice (18) for supply of a hydrocarbonaceous stream. The distributor plate (24) has orifices (28). The swirl register (22) is disposed between the feed orifice (20) for supply of an oxygenous stream and the mixing section (14). The mixing diffuser (16) is connected to the mixing section (14).There is a further proposal of a process for preparing acetylene and synthesis gas by partial oxidation of hydrocarbons with oxygen.